Apparatus for testing electronic devices

ABSTRACT

An apparatus is described for burn-in and/or functional testing of microelectronic circuits of unsingulated wafers. A large number of power, ground, and signal connections can be made to a large number of contacts on a wafer. The apparatus has a cartridge that allows for fanning-in of electric paths. A distribution board has a plurality of interfaces that are strategically positioned to provide a dense configuration. The interfaces are connected through flexible attachments to an array of first connector modules. Each one of the first connector modules can be independently connected to a respective one of a plurality of second connector modules, thereby reducing stresses on a frame of the apparatus. Further features include for example a piston that allows for tight control of forces exerted by terminals onto contacts of a wafer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from U.S. Provisional PatentApplication No. 60/687,502, filed on Jun. 3, 2005, U.S. ProvisionalPatent Application No. 60/682,989, filed on May 19, 2005, and U.S.Provisional Patent Application No. 60/675,546, filed on Apr. 27, 2005which are incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

1). Field of the Invention

This invention relates to an apparatus that is used for full-wafertesting and/or burn-in testing and/or built-in self-testing.

2). Discussion of Related Art

Microelectronic circuits are usually fabricated in and on semiconductorwafers. Such a wafer is subsequently “singulated” or “diced” intoindividual dies. Such a die is typically mounted to a supportingsubstrate for purposes of providing rigidity thereto and electroniccommunication with an integrated or microelectronic circuit of the die.Final packaging may include encapsulation of the die and the resultingpackage can then be shipped to a customer.

It is required that the die or the package be tested before beingshipped to a customer. Ideally, the die should be tested at an earlystage for the purposes of identifying the defects that occur duringearly stage manufacturing.

The earliest stage that a die can be tested is after completion of themanufacture of circuits at wafer level and before a wafer is singulated.Full wafer testing carries with it a number of challenges. One challengein full wafer testing is that there are a large amount of contacts on awafer and that a large number of power, ground, and signal connectionsthus have to be made.

SUMMARY OF THE INVENTION

The invention provides a contactor assembly, including a contactorsupport structure, a plurality of terminals, held by the contactorsupport structure, for contacting respective contacts of a device undertest, at least first and second interfaces, on the contactor supportstructure, each having at least one row of contacts for contacting arespective terminal of a connector, the rows of the contacts of theinterfaces being at an angle between 0 degrees and 180 degrees relativeto one another, and a plurality of conductors, held by the contactorsupport structure, connecting the contacts of the interfaces and theterminals on the contactor support structure to one another.

The angle may be substantially 90 degrees.

The contactor assembly may comprise at least a third of said interfaces,wherein the row of contacts of the third interface is between the row ofcontacts of the first interface and the terminals held by the contactorsupport structure.

The rows of contacts of the first and third interfaces may besubstantially parallel to one another.

The contactor support structure may have two threaded openings atopposing ends of each interface, for securing the respective connectorsto the contactor support structure.

The contactor support structure may include a distribution substrate anda circular contactor substrate secured to the distribution substrate,the terminals held by the contactor support structure being held by thecontactor substrate and the contacts on the contactor support structurebeing on the distribution substrate.

The invention also provides a contactor assembly, including a contactorsupport structure, a plurality of terminals, held by the contactorsupport structure, for contacting respective contacts of a device undertest, at least first and second interfaces, on the contactor supportstructure, each having at least one row of contacts for contacting arespective terminal of a connector, the row of contacts of the secondinterface being between the row of contacts of the first interface andthe terminals held by the contactor support structure, and a pluralityof conductors, held by the contactor support structure, connecting thecontacts of the interfaces and the terminals on the contactor supportstructure to one another.

The contactor assembly may comprise at least a third of said interfaces,wherein the row of contacts of the second interface is between the rowof contacts of the first interface and the terminals held by thecontactor support structure.

The contactor support structure may have two threaded openings atopposing ends of each interface, for securing the respective connectorsto the contactor support structure.

The invention further provides a contactor assembly, including acontactor support structure, a plurality of terminals, held by thecontactor support structure within an inner area of the contactorsupport structure, for contacting respective contacts of a device undertest, a plurality of interfaces on the contactor support structure, eachinterface having at least one row of contacts for contacting arespective terminal of a connector, a combined length of the rows beingmore than a length of a periphery of the inner area, and a plurality ofconductors, held by the contactor support structure, connecting thecontacts of the interfaces and the terminals on the contactor supportstructure to one another.

The rows of the contacts of the interfaces may be at an angle between 0degrees and 180 degrees relative to one another.

A row of contacts of a first of the interfaces may be between a row ofcontacts of a second of the interfaces.

The invention further provides an apparatus for testing an integratedcircuit of a device, including an apparatus frame, a holder, having asurface against which the device is placed, mounted to the apparatusframe, a cartridge frame mounted to the apparatus frame, a contactorsupport structure, a contactor interface on the contactor supportstructure, a plurality of terminals held by the contactor supportstructure, a plurality of conductors, held by the contactor supportstructure, connecting the interface to the terminals, and an actuatorconnected between the cartridge frame and the contactor supportstructure, having first and second portions that are movable relative toone another to move the contactor support structure relative to thecartridge frame and toward the surface of the holder so that theterminals are urged against contacts of the device.

The first and second portions of the actuator may be a cylinder and apiston, respectively, the piston being located in the cylinder so thatthe cylinder and the piston jointly define a volume, further including afluid line connected to the volume to modify a pressure of the volumeand move the piston relative to the cylinder.

A travel sensor for measuring the movement of the contactor supportrelative to the cartridge frame may be provided.

The cartridge frame may include a lower backing plate and a supportstructure, and the travel sensor may include an outer portion attachedto the support structure and an inner portion attached to the backingplate, and actuation of the actuator may cause the relative movementbetween the outer portion and the inner portion.

The travel sensor may measure the change of inductance or capacitancebetween the outer portion and the inner portion.

The invention further provides a cartridge, including a cartridge frame,formations on the cartridge frame for mounting the cartridge frame in afixed position to an apparatus frame, a contactor support structure, acontactor interface on the contactor support structure, a plurality ofterminals held by the contactor support structure, a plurality ofconductors, held by the contactor support structure, connecting theinterface to the terminals, and an actuator connected between thecartridge frame and the contactor support structure, having first andsecond portions that are movable relative to one another to move thecontactor support structure relative to the cartridge frame.

The first and second portions of the actuator may use a cylinder and apiston, respectively, the piston being located in the cylinder so thatthe cylinder and the piston jointly define a volume, further including afluid line connected to the volume to modify a pressure of the volumeand move the piston relative to the cylinder.

A travel sensor for measuring the movement of the contactor supportrelative to the cartridge frame may be provided.

The cartridge frame may include a lower backing plate and a supportstructure, and the travel sensor may include an outer portion attachedto the support structure and an inner portion attached to the backingplate, and actuation of the actuator may cause the relative movementbetween the outer portion and the inner portion.

The travel sensor may measure the change of inductance or capacitancebetween the outer portion and the inner portion.

The invention further provides a method of testing an integrated circuitof a device, including holding the device against a surface of a holder,actuating an actuator to move a contactor support structure relative toa frame and urge terminals on the contactor support structure againstcontacts on the device, and providing signals through the terminals andcontacts to the integrated circuit.

The method further comprises moving the device with the holder relativeto the frame in a direction toward the contactor support structurebefore urging the terminals against the contacts.

The method further comprises utilizing the actuator to move theterminals into contact with the contacts.

The actuator may include a cylinder and a piston in the cylinder, thepiston being moved relative to the cylinder by changing a pressure on asurface of the cylinder.

The method may further include measuring the movement of the actuator.

The method may further include controlling the speed of movement of theactuator.

The invention further provides an apparatus for testing an integratedcircuit of a device, including an apparatus frame; a holder, having asurface against which the device is placed, mounted to the apparatusframe; a cartridge frame mounted to the apparatus frame; a contactorsupport structure; a contactor interface on the contactor supportstructure; a plurality of terminals held by the contactor supportstructure; a plurality of conductors, held by the contactor supportstructure, connecting the interface to the terminals; a variable-forceactuator connected between the cartridge frame and the contactor supportstructure, having first and second portions that are movable relative toone another to move the contactor support structure relative to thecartridge frame and toward the surface of the holder so that theterminals are urged against contacts of the device; and a travel sensorconnected to the cartridge frame for measuring the movement of thecartridge frame relative to the apparatus frame.

The cartridge frame may include a lower backing plate and a supportstructure, and wherein the travel sensor may include an outer portionattached to the support structure and an inner portion attached to thebacking plate, and wherein actuation of the actuator may cause therelative movement between the outer portion and the inner portion.

The device with the holder may be moveable relative to the frame in adirection toward the contactor support structure.

The variable-force actuator may include a piston.

The pressure of the piston may be set so that the piston is in themiddle of its stroke when the terminals are urged against the contactsof the device.

The invention further includes an apparatus for testing an integratedcircuit of a device, including an apparatus frame, an alignmentformation on the apparatus frame, a holder, capable of holding thedevice, mounted to the apparatus frame, a cartridge frame, a contactorsupport structure mounted to the cartridge frame, a plurality ofterminals on the contactor support structure, and a positioningformation on the cartridge frame, the positioning formation mating withthe alignment formation to position the cartridge frame on the apparatusframe in a position wherein the terminals can make contact with contactsof the device upon movement of the terminals and the contacts relativelytoward one another.

The apparatus comprises a plurality of alignment formations on theapparatus frame and a plurality of positioning formations on thecartridge frame, each mating with a respective one of the alignmentformations.

The apparatus of further comprises a retaining mechanism releasablyinterconnecting the apparatus frame and the cartridge frame to preventmovement of the cartridge frame off the apparatus frame when theterminals are urged against the contacts.

The retaining mechanism may be remotely actuable.

The alignment formation may be an opening in the frame, the positioningformation being a positioning pin that is inserted into the opening, andthe retaining formation engaging with a retaining formation on thepositioning pin.

The apparatus further comprises an interface on the contactor supportstructure and a plurality of conductors interconnecting the terminalswith contacts of the interface, and a flexible connector attached to theinterface through which signals can be routed to the terminals and thecontacts on the device.

The invention further provides a cartridge, including a cartridge frame,a plurality of positioning pins on the cartridge, each being insertableinto a respective opening of an apparatus frame, and each having aretaining formation with which a retaining mechanism on the apparatusframe is engageable to secure the cartridge frame to the apparatusframe, a contactor support structure mounted to the cartridge frame, aplurality of terminals on the contactor support structure, each beingpositioned for contacting a respective contact of a device, an interfaceon the contactor support structure, and a plurality of conductorsinterconnecting the terminals with contacts of the interface.

The invention further provides a method for testing an integratedcircuit of a device including moving a positioning formation toward analignment formation to position a cartridge frame on an apparatus framein a position wherein terminals of the cartridge frame can make contactwith contacts of the device upon movement of the terminals and thecontacts relatively toward one another; and engaging the positioningformation with the alignment formation.

The positioning formations may include a plurality of positioning pinsinsertable into a respective opening of the apparatus frame.

The positioning pins may include a retaining formation engageable with aretaining mechanism on the apparatus frame.

The invention further provides a connector system, including a firstframe portion, a connector block support piece held by the first frameportion, a first connector block held by the connector block supportpiece, a plurality of terminals and contacts held by the first connectorblock, a first engagement component mounted to the connector blocksupport piece, a second frame portion, a second connector block held bythe second frame portion, a plurality of terminals and contacts held bythe second connector block, a second engagement component mounted to thesecond frame portion, the second engagement component being releasablyengageable with the first engagement component, and a component actuatorconnected to the second engagement component, the component actuator,upon actuation, causing movement of the second and first engagementcomponents relative to the second frame portion, and movement of theconnector block support piece relative to the first frame portion sothat the contacts on the first connector block come into contact withthe terminals on the second connector block.

The actuator may include a cylinder and a piston in the cylinder, thesecond engagement component being a shaft that extends from the cylinderand having an engagement formation thereon, wherein the first engagementcomponent has an engagement formation thereon and is movable relative tothe connector support piece between a first position, wherein theengagement formation on the first engagement component is disengagedfrom the engagement formation on the second engagement component, and asecond position wherein the engagement formations of the first andsecond engagement components engage with one another.

The invention further provides a connector system, including a firstframe portion, a second frame portion, a plurality of connector sets,each set including a connector block support piece held by the firstframe portion, a first connector block held by the connector blocksupport piece, a plurality of terminals and contacts held by the firstconnector block, a first engagement component mounted to the connectorblock support piece, a second connector block held by the second frameportion, a plurality of terminals and contacts held by the secondconnector block, a second engagement component mounted to the secondframe portion, the second engagement component being releasablyengageable with the first engagement component, and a component actuatorconnected to the second engagement component, and an engager which ismovable between a disengaging position wherein the first engagementcomponents are disengaged from the second engagement components, and anengaging position wherein the engager has moved the first engagementcomponents into engagement with the second engagement components, thecomponent actuator, upon actuation, causing movement of the second andfirst engagement components relative to the second frame portion, andmovement of the connector block support piece relative to the firstframe portion so that the contacts on the first connector block comeinto contact with the terminals on the second connector block.

The connector system further comprises an engager actuator connected tothe engager, the engager actuator moving the engager between theengaging and disengaging positions.

The connector sets may be located in at least one row.

The invention further provides an engager including first engagementcomponents connected with a first connector block having a plurality ofcontacts; second engagement components connected with a second connectorblock having a plurality of terminals; and an actuator to move the firstengagement components from a disengaging position, wherein the firstengagement components are disengaged from the second engagementcomponents, to an engaging position wherein the first engagementcomponents are engaged with the second engagement components to contactthe contacts of the first connector block with the terminals of thesecond connector block.

The first engagement components may be mounted to a first connectorblock support piece, the first connector block support piece supportingthe first connector block and wherein the second engagement componentsmay be mounted to a second connector block support piece, the secondconnector block support piece supporting the first connector block.

The first engagement components may include slider pins, and wherein thesecond engagement components comprise slider openings corresponding tothe slider pins.

The actuator may include a cylinder and a piston in the cylinder.

The actuator may include a cylinder and a piston in the cylinder, thesecond engagement component being a shaft that extends from the cylinderand having an engagement formation thereon, wherein the first engagementcomponent has an engagement formation thereon and is movable relative tothe connector support piece between a first position, wherein theengagement formation on the first engagement component is disengagedfrom the engagement formation on the second engagement component, and asecond position wherein the engagement formations of the first andsecond engagement components engage with one another.

The invention further provides an apparatus for testing an integratedcircuit of a device, including an apparatus frame having first, second,and third portions, a holder for the device mounted to the first portionof the apparatus frame, a plurality of first connector modules held bythe second portion of the apparatus frame, each having a body and aplurality of terminals and contacts on the body, a contactor supportstructure, a plurality of terminals on the contactor support structure,the contactor support structure being positioned so that the terminalsthereon can make contact with contacts on the device, a plurality ofconductors connecting the terminals on the contactor support structurewith the terminals of the first connector modules, and a plurality ofsecond connector modules held by the third portion of the apparatusframe, each having a body and a plurality of terminals and contacts onthe body, the contacts of the first connector modules being engageablewith the terminals of the second connector modules.

The third portion of the apparatus frame may be movable relative to thesecond portion of the apparatus frame to move the second connectormodules relatively toward the first connector modules.

The first connector modules may be located in an array having aplurality of rows and columns.

The first connector modules may be located over a first area and theterminals on the contactor support structure are located over a secondarea, the first area being larger than the second area.

The apparatus comprises a plurality of flexible ribbons, each includinga flexible outer layer and a respective set of the conductors within therespective flexible outer layer.

The body of each respective first connector module may have a pluralityof slots formed therein and the contacts of the first connector moduleare within the slots, and wherein each respective second connectormodule has a plurality of substrates held by the body of the secondconnector module and the terminals of the second connector module beinglocated on the substrates, the substrates beirig insertable into theslots.

The invention further provides a cartridge, including a cartridge frame,a plurality of first connector modules held by the cartridge frame, eachhaving a body and a plurality of terminals and contacts on the body, acontactor support structure mounted to the cartridge frame, a pluralityof terminals, for contacting contacts on a device, on the contactorsupport structure, and a plurality of conductors connecting theterminals on the contactor support structure with the terminals of thefirst connector modules.

The first connector modules may be located in an array having aplurality of rows and columns.

The first connector modules may be located over a first area and theterminals on the contactor support structure are located over a secondarea, the first are being larger than the second area.

The cartridge comprises a plurality of flexible ribbon, each including aflexible outer layer and the conductors within the flexible outer layer.

The body of each respective first connector module may have a pluralityof slots formed therein and the contacts of the first connector moduleare within the slots.

The invention further provides a method for testing an integratedcircuit of a device including providing a plurality of first connectormodules held by a portion of an apparatus frame, the plurality of firstconnector modules including a plurality of terminals and contacts;providing a plurality of second connector modules held by a differentportion of the apparatus frame, the plurality of second connectormodules including a plurality of terminals and contacts; and engagingthe contacts of the first connector modules with the terminals of thesecond connector modules.

The portion of the apparatus frame holding the second connector modulesmay be moveable relative to the portion of the apparatus frame holdingthe first connector modules.

The invention also provides an apparatus for testing integrated circuitsof a plurality of devices, comprising at least one holder to hold theplurality of devices, a tester system having a plurality of outputchannels and an interconnection scheme to connect the channels to aplurality of contacts of the plurality of devices, the contacts beingconnected to the integrated circuits, a computer system having memory, atest program stored in the memory, the test program having a series ofinstructions written for testing one of the devices, a configurationfile stored in the memory, the configuration file representing arelationship between the channels and the contacts of the plurality ofdevices, and a test application that utilizes the test program and theconfiguration file to provide signals in accordance with the series ofinstructions of the test program through the channels and theinterconnection scheme to the contacts of the plurality of devices andthe integrated circuits.

The interconnection scheme may also include a plurality of configurablepattern generator boards, each representing a respective zone, theconfiguration file having a zone number field indicating a plurality ofrespective ones of the zones.

The interconnection scheme may also have a plurality of boards insertedinto a plurality of slots, the configuration file having a slot numberfield indicating a plurality of respective ones of the slot numbers.

The configuration file may have channel, number, and pad labeled fieldsto represent the relationship between the channels and the contacts ofthe plurality of devices.

The devices may be located in rows and columns, the configuration filehaving column and row fields indicating the respective row and column ofeach respective die.

The interconnection scheme may have a line connected to a set of thedevices and a plurality of respective select lines connected torespective ones of the devices of the set, further comprising a sharedresources map in the memory, the shared resources map representing arelationship between the select lines and the devices of the set.

The select lines may be grouped into chip select states.

The shared resources map may form part of the configuration file.

The apparatus may further comprise a test results file stored in memory,and may have a processing application that utilizes the test resultsfile and the configuration file to provide a test output and optionaltest input.

The test application may utilize the test results file to selectivelymodify signals in accordance with the series of instructions of the testprogram through the channels and the interconnection scheme to thecontacts of the plurality of devices and the integrated circuits.

The test application may utilize the test results file to selectivelymodify the sequence of signals in accordance with the series ofinstructions of the test program through the channels and theinterconnection scheme to the contacts of the plurality of devices andthe integrated circuits.

The invention also provides a method of testing integrated circuits of aplurality of devices, comprising storing a test program having a seriesof instructions written for testing one of the devices, storing aconfiguration file representing a relationship between a plurality ofchannels and a plurality of contacts of the plurality of devices, andproviding signals in accordance with the series of instructions of thetest program through the channels to the plurality of contacts of theplurality of devices, utilizing the configuration file to map the seriesof instructions of the test program to the plurality of contacts of theplurality of devices.

The devices may be a portion of a wafer.

The method may further comprise uploading test results provided from thedevices through the configuration scheme and utilizing the test resultsand the configuration file to prepare a test report.

The test results may be uploaded from memory on a plurality of boardsincluding at least one driver board and at least one power board.

The test results may be used to modify the signals provided to theplurality of devices and the integrated circuits.

The test results may be used to modify the application of power providedto the plurality of devices and the integrated circuits.

The test results may be used to modify the signals provided to theplurality of devices and the integrated circuits to balance their powerconsumption.

The test results may be used to selectively sort devices into groupsbased upon their power consumption.

The test results may be used to modify the sequence of signals providedto the plurality of devices and the integrated circuits.

The invention may also include a software assembly method, comprisingstoring a plurality of net files, each net file having informationrepresenting a scheme of current passing through conductors of arespective electrical subassembly, providing an input of aninterconnection scheme of a plurality of the electrical subassembliesconnected to one another; and assembling a plurality of the net filesbased on the interconnection scheme to construct a configuration filehaving information representing flow of current through the electricalsubassemblies of the interconnection scheme.

The input may be provided manually.

The electrical subassemblies may include pattern generator, driver, andpower boards.

The electrical subassemblies may include a plurality of patterngenerator, driver, and power boards divided into physical zones witheach physical zone including one pattern generator board, at least onedriver board, and at least one power board connected to one another.

The configuration file may have a zone name field indicating a pluralityof respective ones of the physical zones.

Physical zones having the same zone name field may be grouped into alogical zone.

The electrical subassemblies in the logical zone may be of the same typeand run the same test program at the same time.

The configuration file may have channel number and pad label fields torepresent a relationship between channels and contacts of a plurality ofdevices.

The interconnection scheme may have a line connected to a set of thedevices and a plurality of respective select lines connected torespective ones of the devices of the set, further comprising using thenet files to construct a shared resources map representing arelationship between the select lines and the devices of the set.

The select lines may be grouped into chip select states.

The invention may include a software assembler application, comprising aplurality of net files, each file having information representing ascheme of current passing through conductors of a respective electricalsub assembly; an input module to provide an input of an interconnectionscheme of a plurality of electrical sub assemblies, and an assemblymodule that assembles a plurality of the net files based on theinterconnection scheme and constructs a configuration file havinginformation representing flow of current through the electrical subassemblies of the interconnection scheme.

The input module may include an interface with a list of selectableinputs.

The interface may allow an operator to select the input of theinterconnection scheme.

The electrical subassemblies may be selected from one or more of thegroup consisting of a pattern generator board, driver board and a powerboard.

The input may include how the electrical subassemblies are to beconnected to one another.

The invention may include an apparatus for testing a device having anintegrated circuit, comprising a frame including a base portion, andtest head and thermal system portions secured to the base portion, aholder secured to the base portion, the holder being capable of holdingthe device, a test head mounted to the test head portion in a positionsuch that electric signals can be sent through the test head to theintegrated circuit of the device, and a thermal system located in aposition to cool components of the test head, and being mounted throughthe thermal system portion to the base portion.

The thermal system may be mounted through the thermal system portion tothe base portion without being mounted to the test head portion.

The test head may include a test head support structure, a plurality ofelectric components mounted to the test head support structure, and apanel that forms a passage through which air can flow before flowingover the electric components.

The electric components may be boards, the test head support structurehaving a plurality of slots that hold the boards.

The thermal system may include a shell through which the air can flowand at least one heat dissipation device in the shell, the shell formingan interface with the panel, with a gap being defined between the shelland the panel.

The heat dissipation device may include a plurality of fins over whichthe air flows.

The thermal system may include a fan that moves the air through theshell.

The thermal system may include a variable frequency drive to vary thespeed of the fan.

The thermal system may include a thermocouple in the test head portion,and wherein the variable frequency drive varies the speed of the fan inaccordance with a measurement of the thermocouple.

The thermal system portion and the test head portion may be mounted forpivotal movement relative to one another.

The invention may have an apparatus for testing a device having anintegrated circuit, comprising a base portion, a holder for the devicemounted to the base portion, a test head portion and a thermal systemportion mounted to the base portion, a test head mounted to the testhead portion, the test head including a test head support structure, aplurality of electric components mounted to the test head supportstructure, and a panel that forms a passage through which air can flowbefore flowing over the electric components, and a thermal systemmounted through the thermal system frame to the base portion, thethermal system including a shell through which the air can flow and atleast one heat dissipation device in the shell, the shell forming aninterface with the panel, with a gap being defined between the shell andthe panel.

The electric components may be boards, the test head support structurehaving a plurality of slots that hold the boards, and the thermal systemincludes a fan that moves the air through the shell.

The thermal system portion and the test head portion may be mounted forpivotal movement relative to one another.

The invention further provides a method for testing a device having anintegrated circuit including electrically connecting a tester apparatuswith the device; and cooling the tester apparatus with a thermal systemwithout the thermal system contacting the tester apparatus.

The test head may include a test head support structure, a plurality ofelectric components mounted to the test head support structure, and apanel that forms a passage through which air can flow before flowingover the electric components; and the thermal system may be mountedthrough the thermal system frame to the base portion, and the thermalsystem may include a shell through which the air can flow and at leastone heat dissipation device in the shell, the shell forming an interfacewith the panel, with a gap being defined between the shell and thepanel.

The method may further include moving air through the shell.

A fan may move air through the shell.

Cooling the tester apparatus may include recirculating air from thethermal system back to the tester apparatus.

The thermal system may include a fan controllable by a variable speeddrive.

The thermal system may include a thermocouple connected with the testsystem, the thermocouple in communication with the variable speed driveof the fan.

The method may further include adjusting the speed of the fan inaccordance with a measurement of the thermocouple.

Cooling the test system may include controlling the temperature of thetest system.

The invention may include a tester apparatus, comprising at least onepower terminal for making contact with a power contact of a devicecarrying an integrated circuit, a power supply circuit configured tosupply a plurality of different voltages, and at least one electric pathconnecting the power supply circuit with the power terminal.

The apparatus may further comprise an apparatus frame, a holder for thedevice mounted to the frame, and a contactor support structure, thepower terminal being located on the contactor support structure.

The apparatus may further comprise a power board substrate, the powersupply circuit and a portion of the electric path being carried by thepower board substrate.

The power supply circuit may include a power input circuit providing astep voltage, a length of time that the step voltage is high during aperiod being adjustable while maintaining the period, and a maximumvoltage constant, and a power converter circuit, connected to the powerinput circuit, converting the step voltage to a supply voltage, amagnitude of the supply voltage being related to the time that the stepvoltage is high during each period of the step voltage.

The apparatus may further comprise a plurality of power terminals, eachfor making contact with a respective contact of a respective devicecarrying a respective integrated circuit, and a plurality of electricpaths, each connecting the power supply circuit to a respectiveterminal.

A plurality of the electric paths may be at a plurality of differentvoltage levels.

An adjustment in a voltage provided by the power supply circuit maychange voltages of a subset of the electric paths in unison, so that theelectric paths of the subset are always at the same voltage.

The plurality of different voltages may include a voltage output of 0.5Vto 12V at a current of at least 200 mA.

The plurality of different voltages may include a voltage output of 0.1Vto 5V at a current of at least 500 mA.

The invention further provides a method for testing an integratedcircuit of a device including supplying a plurality of differentvoltages to at least one power terminal; and contacting the at least onepower terminal with a power contact of the device.

Supplying a plurality of different voltages may include providing a stepvoltage; and converting the step voltage to a supply voltage.

The step voltage has a length of time that the step voltage is highduring a period being adjustable while maintaining the period, andwherein the magnitude of the supply voltage may be related to the timethat the step voltage is high during each period of the step voltage.

The method may further include supplying a plurality of differentvoltages to a plurality of power terminals; and contacting the pluralityof power terminals with a plurality of respective contacts of thedevice.

Supplying a plurality of different voltages to a plurality of powerterminals may include supplying each power terminal with a differentvoltage level.

The method may further include adjusting the supplied voltage.

Adjusting the supplied voltage may change voltages of a subset of thepower terminals in unison, the subset of power terminals always being atthe same voltage.

The invention may include an apparatus for testing integrated circuitsof a plurality of devices, comprising a plurality of power terminals,each for making contact with a respective power contact of a respectiveone of the devices, at least one power supply, a plurality of electricpaths, each connecting said at least one power supply to a respectiveone of the power terminals, and a plurality of individual shut-offcircuits, each including a respective current sense circuit detecting arespective current in a respective one of the electric paths, and arespective power switch in a respective one of the electric paths, eachpower switch being connected to a respective current sense circuit andturning off when the current detected by the respective current sensecircuit exceeds a predetermined maximum current.

Each shut-off circuit may include a logic device that at least delaysactivation of the power switch after the current exceeds thepredetermined maximum current.

The shut-off circuit may include a logic switch that turns a shut-offvoltage on, the shut-off voltage being provided to the power switch toturn the power switch off.

The power switch may be a MOSFET.

The invention may include a method of testing integrated circuits of aplurality of devices, comprising providing a power voltage to eachintegrated circuit, providing signals to each integrated circuit,detecting a power current that is provided to each integrated circuit,and individually turning the power voltage to one of the integratedcircuits off, if the power current exceeds a predetermined maximumcurrent.

The method may further include delaying turning the power voltage to theintegrated off when the power current exceeds a predetermined maximumcurrent.

Turning the power voltage to one of the integrated circuits off mayinclude turning a shut-off voltage on.

The method may further include detecting a power current provided to apower terminal of the device; and turning the power to the device off ifthe power current exceeds a predetermined maximum current.

The method may further include detecting a power voltage provided to apower terminal of the device; and turning the power to the device off ifthe power voltage exceeds a predetermined maximum voltage.

The invention further provides an apparatus for testing an integratedcircuit of a device including a power supply; a test signal line; and aswitching circuit between the power supply and a terminal for contactinga contact of the device, the switching circuit drawing current from theterminal when the test signal is provided to the switching circuit.

The switching circuit may include a resistor and a MOSFET.

The resistor may be connected to the power supply, and the MOSFET isconnected in series after the resistor.

The test signal may be provided to the MOSFET.

The MOSFET may draw power from the power supply when the test signal isprovided to the switching circuit.

The invention further provides a method for testing an integratedcircuit of a device include providing a test signal to a switchingcircuit; and drawing current from the device to the switching circuitwhen the switching current receives the test signal.

The switching circuit may include a MOSFET, and wherein the test signalis provided to the MOSFET.

The invention further provides a method for testing an integratedcircuit of a device including providing a test signal to a switchingcircuit; disabling current to the device; and providing the current tothe switching circuit.

The switching circuit may include a MOSFET, and wherein the test signalis provided to the MOSFET.

The invention may include a tester apparatus, comprising at least onepower terminal for making contact with a power contact of a devicecarrying an integrated circuit, a power supply, and an electrical pathconnecting the power supply to the power terminal, the electrical pathincluding at least a first set of power conductors electrically parallelto one another, having respective first ends connected to one anotherand respective second ends connected to one another.

The tester apparatus may further comprise a power board substrate,wherein the first set of power conductors is carried by the power boardsubstrate.

The first set of power conductors may be traces on the power boardsubstrate.

The electrical path may include a second set of power conductors thatare electrically in series with the first set of power conductors, thesecond set of power conductors being electrically parallel to oneanother, having respective first ends connected to one another andrespective second ends connected to one another.

The second set of power conductors may form part of a flexibleattachment that further includes a nonconductive layer, the powerconductors being held within the nonconductive layer.

The invention further provides a method for testing an integratedcircuit of a device including connecting a power supply with a powerterminal of the device; providing a plurality of power conductorsbetween the power supply and the power terminal conductors havingrespective first ends connected to one another and respective secondends connected to one another; and conducting current from the powersupply through the plurality of power conductors in parallel.

Conducting the current in parallel may obtain a high-frequency response.

The invention further provides an apparatus for testing an integratedcircuit of a device including a pattern generator board; a driver boardconnected to the pattern generator board; a power board; aninterconnection scheme connecting the driver board and the power boardwith the device.

Each of the pattern generator board, driver board, power board andinterconnection scheme may be configurable.

The number of each of the pattern generator board, driver board and thepower board may be configurable.

The interconnection scheme may include at least a first set of powerconductors electrically parallel to one another, having respective firstends connected to one another and respective second ends connected toone another.

The interconnection scheme may further include a second set of powerconductors that are electrically in series with the first set of powerconductors, the second set of power conductors being electricallyparallel to one another, having respective first ends connected to oneanother and respective second ends connected to one another.

The invention may include an apparatus for testing a device carrying anintegrated circuit, comprising a power terminal for making contact witha power contact of the device, a power supply, an electrical power forcepath connecting the power supply to the power terminal, a groundterminal for making contact with a grand contact of the device, and aground sense feedback circuit connected between the ground terminal andthe electrical power path, the ground sense feedback circuit utilizing avoltage sensed by the ground terminal to modify a voltage providedthrough the electrical power force path to the power contact.

The apparatus may further comprise a plurality of ground terminals, theground sense feedback circuit being connected to the plurality of groundterminals.

The apparatus may further comprise a plurality of power terminals, eachfor making contact with a respective power contact of a respectivedevice, and a plurality of electrical power force paths, each connectinga respective power terminal to the power supply.

The ground sense feedback circuit may be connected to the plurality ofelectrical power force paths to modify a voltage of each electricalpower force path.

The power sense feedback circuit may be connected between the powerterminal and the electrical path, the power sense feedback circuitutilizing a voltage sensed by the power terminal to modify a voltageprovided through the electrical force path to the power contact.

The power sense feedback circuit may have a reference voltage line,inputs from the reference voltage line and the power terminals beingcompared to determine a modification of the voltage provided through theelectrical power force path.

A voltage sensed by the ground feedback circuit may be used to modify avoltage of the reference voltage line.

The invention may include a method of testing a device having anintegrated circuit, comprising providing a power voltage to a powercontact of the device, sensing a ground voltage on a ground contact ofthe device, and modifying the power voltage based on the ground voltagethat is sensed.

The method may further comprise sensing the power voltage provided tothe power contact, and modifying the power voltage based on the powervoltage that is sensed.

Sensing the ground voltage may include adding the ground voltage to avariable input voltage.

Modifying the power voltage may be based on a sum of the ground voltageand the power voltage.

Modifying the power voltage based on the ground voltage that is sensedmay include, if the sensed ground voltage is not zero, driving avariable output voltage to the sum of the ground voltage and thevariable input voltage.

Modifying the power voltage based on the ground voltage that is sensedmay further include providing the variable output voltage to the powercontact of the device.

The invention may include an apparatus for testing an integrated circuitof a device, comprising a voltage source, a voltage switch connected tothe voltage source, a signal source connected to the voltage switch, asignal provided by the signal source switching the voltage switch sothat an output of the signal switch switches between respective low- andhigh-voltage states to create a series of voltage steps, a dampingcircuit having an input connected to the output of the signal switch,the damping circuit reducing a slew rate each voltage step, and havingan output providing a series of dampened voltage steps, and a signalterminal, connected to the output of the damping circuit, for contactinga contact of the device.

The apparatus may comprise a plurality of signal terminals, eachconnected to the damping circuit but located at different distances fromthe damping circuit as measured along a path that current flows from thedamping circuit.

The damping circuit may include a resistor in series between the voltageswitch and the terminal and a capacitor connected between a terminal ofthe resistor and ground.

The apparatus may further comprise a digital-to-analog converter (DAC),a microprocessor bus line connected to the DAC for data representing thehigh and low voltages into the DAC, the high and low voltages beingprovided by two output terminals of the DAC.

The voltage source may be connected between two input terminals of theDAC.

The two input terminals of the DAC may be held at positive and negativevoltages respectively.

The apparatus may further comprise a ground sense line connected to aground contact of the device, the input voltages of the DAC being inpart driven by a voltage on the ground sense line.

The invention further provides a method for testing an integratedcircuit of a device including providing a signal to a voltage switch,the voltage switch switching between respective low- and high-voltagestates to create a series of voltage steps to create a series of voltagesteps; reducing a slew rate of each voltage step to provide a series ofdampened voltage steps; and providing the series of dampened voltagesteps to a contact of the device.

The series of dampened voltage steps may be provided to a plurality ofcontacts of the device, each of the contacts at different distances fromthe path that current flows.

The invention further provides a damping circuit for an apparatus fortesting an integrated circuit device including a voltage switch; asignal terminal for contacting a contact of the device; a resistor inseries between the voltage switch and the signal terminal; and acapacitor connected between a terminal of the resistor and the signalterminal.

The damping circuit may further include a plurality of signal terminals,the capacitor connected between a terminal of the resistor and theplurality of signal terminals, the signal terminals at differentdistances from the capacitor as measured along a path that current flowsfrom the capacitor.

The invention may include an apparatus for testing an integrated circuitof a device, comprising at least one frame, a holder for the device,secured to the frame, a support structure held by the frame, a pluralityof terminals held by the support structure, the holder and supportstructure being movable relative to one another so that each one of theterminals releasably makes contact with a respective contact of thedevice, a power source to supply AC and DC power, a power electricalpath connecting the power source to a power terminal of the terminalsheld by the support structure, a signal source, a plurality of signalelectrical paths, each connecting the signal source to a respectivesignal terminal of the terminals held by the support structure, a groundplate connected to the at least one frame, an AC ground pathinterconnecting the terminals and the ground plate, and a DC ground pathinterconnecting the terminals and the ground plate.

The AC ground path and the DC ground path may be electrically separated.

The AC ground path may have a resistance between 0.5 and 1.5 ohms andthe DC ground path has a resistance between 0.003 and 0.015 ohms.

The apparatus may include a ground pin, the ground pin connected to thepower source.

The physical space between the AC power provision, signal line and ACpower ground may be small.

The DC ground path may be connected to the support structure.

The invention further provides a method for testing an integratedcircuit of a device including holding the device against a surface of atester; contacting terminals on the tester to contacts on the device;providing signals through the terminals and contacts to the integratedcircuit; providing AC and DC power to the terminals.

Providing the AC and DC power to the terminals may include electricallyseparating the AC and DC power.

The method may further include providing separate AC ground and DCground paths.

The invention further provides a board for providing power to anapparatus for testing an integrated circuit of a device including apower source to supply AC and DC power; a power electrical path toconnect the power source to a power terminal of the device; a groundpin; an AC ground path interconnecting terminals of the device and theground pin; and a DC ground path interconnecting terminals of the deviceand the ground pin.

The AC ground path and the DC ground path may be electrically separated.

The AC ground path may have a resistance between 0.5 and 1.5 ohms andthe DC ground path may have a resistance between 0.003 and 0.015 ohms.

The physical space between the AC power provision, signal line and ACpower ground may be small.

The board may further include a power board substrate, the power source,power electrical path, ground pin, and AC and DC ground paths providedon the power board substrate.

The invention may include an apparatus for testing an integrated circuitof a device, comprising at least one frame, a holder for the device,secured to the frame, a support structure held by the frame, a pluralityof terminals held by the support structure, the holder and supportstructure being movable relative to one another so that each one of theterminals releasably makes contact with a respective contact of thedevice, a power source, a power electrical path connecting the powersource to a power terminal of the terminals held by the supportstructure, a signal source, and a plurality of signal electrical paths,each connecting the signal source to a respective signal terminal of theterminals held by the support structure.

The invention further provides an apparatus for testing an integratedcircuits on devices including a plurality of electrical subassembliesincluding a plurality of pattern generator, driver, and power boardsdivided into physical zones with each physical zone including onepattern generator board, at least one driver board, and at least onepower board connected to one another; and a configuration file havinginformation representing flow of current through the electricalsubassemblies connected to one another in an interconnection scheme,wherein the electrical subassemblies are organized into at least onelogical zone, and wherein the logical zone comprises a plurality ofpattern generators.

The electrical subassemblies may be organized into a plurality oflogical zones, and wherein one or more of the logical zones comprises aplurality of pattern generators.

The at least one logical zone may be divided into a plurality of thephysical zones.

The configuration file may have a zone name field indicating a pluralityof respective ones of the physical zones.

Physical zones having the same zone name field may be grouped into alogical zone.

The electrical subassemblies in the logical zone may be of the same typeand run the same test program at the same time.

The electrical subassemblies in each of the plurality of logical zonesmay be of the same type and run the same test program at the same time,and wherein each of the plurality of logical zones runs a different testprogram at the same time.

The invention further provides a method for testing integrated circuitson devices including running more than one test program on the devicesimultaneously.

Running more than one test program on the device simultaneously mayinclude providing a plurality of electrical subassemblies including aplurality of pattern generator, driver, and power boards divided intophysical zones with each physical zone including one pattern generatorboard, at least one driver board, and at least one power board connectedto one another, the electrical subassemblies are organized into at leastone logical zone, and wherein the logical zone comprises a plurality ofpattern generators; providing a configuration file having informationrepresenting flow of current through the electrical subassembliesconnected to one another in an interconnection scheme; and running atest program through the at least one logical zone.

Running more than one test program on the device simultaneously mayinclude providing a plurality of electrical subassemblies including aplurality of pattern generator, driver, and power boards divided intophysical zones with each physical zone including one pattern generatorboard, at least one driver board, and at least one power board connectedto one another, the electrical subassemblies are organized into aplurality of logical zones, and wherein each of the logical zonescomprises a plurality of pattern generators; providing a configurationfile having information representing flow of current through theelectrical subassemblies connected to one another in an interconnectionscheme; and running a test program through each of the logical zonessimultaneously.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is further described by way of example with reference tothe accompanying drawings wherein:

FIG. 1 is a perspective view of an apparatus, according to an embodimentof the invention, which can be used for full-wafer testing and/orburn-in and/or built-in self-testing;

FIG. 2 is a view similar to FIG. 1 wherein a thermal system frameportion is rotated approximately 45 degrees counterclockwise;

FIG. 3 is a sectioned perspective view from below illustrating areplaceable cartridge forming part of the apparatus of FIGS. 1 and 2;

FIG. 4 is a cross-sectional side view illustratively illustrating acontactor assembly forming a lower part of the cartridge of FIG. 3;

FIG. 5 is a bottom plan view of one interface of contacts on adistribution board of the contactor assembly of FIG. 5;

FIG. 6 is a bottom plan view of the contactor assembly of FIG. 5,particularly illustrating a layout of a plurality of interfaces of FIG.5;

FIG. 7 is a cross-sectional side view of a portion of the cartridge ofFIG. 3, particularly illustrating an actuator mechanism that is used tomove the contactor assembly relative to a backing plate of a cartridgeframe, and further illustrating a wafer holder that holds a wafer;

FIG. 8 is a view similar to FIG. 7, after the wafer holder has moved thewafer in to a position below terminals of the contactor assembly;

FIG. 9 is a view similar to FIG. 8, after the actuator mechanism is usedto move the terminals into contact with contacts on the wafer;

FIG. 10 is a time chart illustrating a force that is created by a pistonof the actuator mechanism;

FIG. 11 is a cross-sectional side view particularly illustrating onealignment and locking formation of the cartridge of FIG. 3 and onealignment and locking mechanism secured to an upper portion of a base ofa frame of the apparatus shown in FIGS. 1 and 2;

FIG. 12 is a view similar to FIG. 11, after the alignment and lockingmechanism is used to align the formation, and the formation is removablyengaged with the alignment and locking mechanism;

FIG. 13 is a cross-sectional side view particularly illustrating onefirst connector set of the cartridge of FIG. 3, one second connector setsecured to a hinge portion of the frame of the apparatus of FIGS. 1 and2;

FIG. 14 is partially cross-sectioned side view illustrating a firstconnector module forming part of the first connector set of FIG. 13;

FIG. 15 is a view similar to FIG. 13, after an engager is used to rotatea spherical inner engagement surface of a first engagement componentforming part of the first connector set over a spherical engager formingpart of a second connector set;

FIG. 16 is a view similar to FIG. 15, after engagement of the firstconnector set with the second connector set;

FIG. 17 is a perspective view of the cartridge of FIG. 3, specificallyillustrating the layout and configuration of a plurality of firstconnector sets of FIG. 13;

FIG. 18 is a perspective view from below illustrating a layout of aplurality of second connector sets of FIG. 13;

FIG. 19 is a perspective view of a portion of the apparatus shown inFIG. 2, wherein the thermal system frame portion is rotatedapproximately 135 degrees counterclockwise, and a test head frameportion is rotated approximately 90 degrees to the right;

FIG. 20 is an end view illustrating in block diagram form the layout ofpower, driver, and pattern generator boards when viewed from the left inFIG. 19;

FIG. 21 is a cross-sectional side view parallel to two of the boardsillustrated in FIG. 20, further illustrating a thermal system that isused to cool the boards;

FIG. 22 is a block diagram of components of the apparatus of FIG. 1,further illustrating a computer system of the apparatus, the computersystem holding a configuration file representing a configuration of atester system of the apparatus;

FIG. 23 is a flow chart of how the apparatus of FIG. 19 is used;

FIGS. 24A and 24B show a block diagram illustrating a database structureof the configuration file;

FIG. 25 is a block diagram of a software assembler application that isused to construct the configuration file from a plurality of net files;

FIG. 26 is a flowchart of how the software assembler application of FIG.22 assembles the configuration file;

FIG. 27 is a block diagram of electrical components of the apparatus ofFIG. 1;

FIG. 28 is a block diagram of components of a power board illustrated inFIGS. 22 and 27, and connections made to the power board;

FIG. 29 is a circuit diagram illustrating components that are replicatedon the power board of FIG. 28;

FIG. 30 is a circuit diagram illustrating components that are replicatedon a driver board illustrated in FIGS. 22 and 27; and

FIG. 31 is a circuit diagram illustrating a termination that is used inconventional design for purposes of damping a test signal.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1 and 2 of the accompanying drawings illustrate an apparatus 10,which is particularly suitable for full-wafer testing of microelectroniccircuits of unsingulated wafers and/or burn-in testing of unsingulatedwafers and/or built-in self-testing of unsingulated wafers. Theapparatus 10 includes a frame 12 and a number of modules mounted to theframe 12 including a wafer loader 14, a probing subassembly 16, acartridge 18, a test head 20, and a thermal system 24.

The frame 12 has a prober base portion 26, a thermal system frameportion 28, and a test head frame portion 30. The thermal system frameportion 28 is pivotally mounted to the prober base portion 26. The testhead frame portion 30 is pivotally mounted to the thermal system frameportion 28. The probing subassembly 16 and the cartridge 18 are mountedto lower and upper portions 32 and 34 respectively of the prober baseportion 26, the test head 20 and the thermal system 24 are mounted tothe test head frame portion 30 and the thermal system frame portion 28respectively.

The thermal system frame portion 28 can, for example, be pivoted betweena position as shown in FIG. 1 wherein the thermal system frame portion28 is over the prober base portion 26, and a position as shown in FIG. 2wherein the pivot arm portion is pivoted approximately 45 degreescounterclockwise to the left. Pivoting of the thermal system frameportion 28 into the position shown in FIG. 2 moves the test head 20 awayfrom the cartridge 18. Access is thereby gained to the cartridge 18 forpurposes of maintenance to or replacement of the cartridge 18.

As illustrated in FIG. 3, the cartridge 18 includes a cartridge frame38, alignment pins 40 for aligning and locking the cartridge frame 38 ina fixed position, a contactor assembly 42, a plurality of firstconnector sets 44, and a plurality of flexible attachments 46 connectingthe contactor assembly 42 to the first connector sets 44.

As shown in FIG. 4, the contactor assembly 42 includes a distributionboard 48, a contactor board 50 and fasteners 52 that secure thecontactor board 50 to the distribution board 48.

Distribution board 48 has a force distribution substrate 55, a thermalexpansion equalization substrate 57, and an electrical distributionsubstrate 54, a plurality of terminals 56 formed on the electricaldistribution substrate 54, a plurality of contacts 58 formed on theelectrical distribution substrate 54, and a plurality of conductors 60carried within the electrical distribution substrate 54. The terminals56 and the contacts 58 are formed on the same side but on differentareas of the electrical distribution substrate 54. Each conductor 60interconnects a respective one of the terminals 56 with a respective oneof the contacts 58.

The contactor board 50 includes a contactor substrate 62 having firstand second pieces 64 and 66, a collar 67, and a plurality of pins 68.One end of each pin 68 is inserted through an opening in the first piece64, and then inserted through an opening in the second piece 66. Eachpin 68 has a central body that is larger than its ends so that it isheld in place by the opening in the second piece 66. The collar 67 isused to align the first and second pieces 64 and 66 relative to oneanother. One end of each pin 68 forms a contact 70 that is placedagainst a respective terminal 56 of the distribution board 48. Anopposing end of each pin 68 forms a terminal 72 that can touch a contact74 on a wafer 76. The fasteners 52 may, for example, be bolts, eachhaving a shank that is inserted though an opening in the contactorsubstrate 62, and thread on the shank is then screwed into a threadedopening in the electrical distribution substrate 54. The electricaldistribution substrate 54, the contactor substrate 62, forcedistribution substrate 55, expansion equalization substrate 57, and thefasteners 52 jointly form a support structure 80 with the terminals 72extending from the support structure 80. The pins 68, terminals 56,conductors 60, and contacts 58 form conductive links to and from theterminals 72.

Each one of the flexible attachments 46 has a flexible nonconductiveouter layer 82, a plurality of conductors 84 held within the outer layer82 and separated from one another by the material of the outer layer 82,a plurality of open terminals 86 at ends of the respective conductors84, and a plurality of electrically conductive bumps 88, each on arespective one of the terminals 86. Each one of the conductive bumps 88is placed against a respective one of the contacts 58 of thedistribution board 48. A clamp piece 90 is placed over an end of theflexible attachment 46. Fasteners 9 are used to secure the clamp piece90 to the electrical distribution substrate 54 and provide a force thatclamps the end of the flexible attachment 46 between the clamp piece 90and the electrical distribution substrate 54.

As further shown in FIG. 5, the contacts 58 form an interface 92. Theinterface 92 has two parallel rows of the contacts 58. Two of thecontacts 58 g are ground contacts that extend from one of the rows tothe other and are located at opposing ends of the rows. Threadedopenings 94 are formed on opposing ends of the interface 92 into theelectrical distribution substrate 54. Each one of fasteners 91 in FIG. 4has a respective head and a respective threaded shank extending from thehead. The head rests on the clamp piece 90 and the shank is screwed intoone of the threaded openings 94 in FIG. 5. A compliant member 93 islocated between the clamp piece 90 and the flexible nonconductive outerlayer 82 to distribute a force created by the clamp piece 90 to ensureuniform contact by the electrically conductive bumps 88.

Referring to FIG. 6, the electrical distribution substrate 54 is squareand has a periphery formed by four sides 98. The contactor substrate 62has a circular periphery 100 within the four sides 98. A plurality ofinterfaces 92 such as the interface 92 of FIG. 5 are provided on an areaof the electrical distribution substrate 54 outside the circularperiphery 100. The locations and orientations of the interfaces 92 areselected to provide a relatively dense configuration. The combinedlength of all the interfaces 92 is more than the length of the circularperiphery 100. The combined length of the interfaces 92 is also morethan the combined length of the sides 98. The interfaces 92 in eachrespective quarter 102, 104, 106 and 108 are all aligned in the samedirection.

The interfaces 92 of the juxtaposed quarters 102 and 106 are each at anangle 110 of 45 degrees relative to a centerline 112 through thedistribution substrate 94. The interfaces of the juxtaposed quarters 104and 108 are each at an angle 114 of 135 degrees relative to thecenterline 112 as measured in the same direction as the angle 110.

Each one of the quarters 102, 104, 106 or 108 has ten of the interfaces92A to 92J. The interfaces 92C, 92D, and 92E are parallel to one anotherbut at different distances from a center point 116 of the contactorsubstrate 62. The interfaces 92F, 92G, and 92H are parallel to oneanother but at different distances from the center point 116. Theinterfaces 92C and 92F are in line with one another, as are theinterfaces 92D and 92G and the interfaces 92E and 92H. The interfaces92B and 92I are in line with one another but form a row that is closerto the center point 116 than the row formed by the interfaces 92C and92F. The interfaces 92B and 92I are also spaced further from one anotherthan the interfaces 92C and 92F. The interfaces 92A and 92J also form arow that is closer to the center point 116 than the row formed by theinterfaces 92B and 92I.

Each one of the quarters 102, 104, 106, and 108 has an arrangement often of the interfaces 92 that is similar to the arrangement ofinterfaces 92A to 92J. The arrangement is rotated through 90 degreesabout the center point 116 when moving from the quarter 108 to thequarter 102. Similarly, the arrangement is rotated through another 90degrees when moving from the quarter 102 to the quarter 104, etc.

A respective flexible attachment 46 is connected to each respective oneof the interfaces 92. The arrangement of the interfaces 92 allows for“fanning-in” or “fanning-out” of a large number of electrical paths toor from a relatively dense arrangement of the terminals 72 of thecontactor board 50.

Referring again to FIG. 3, the cartridge frame 38 includes a lowerbacking plate 120, upper support pieces 122, and connecting pieces 124that mount the upper support pieces 122 to the backing plate 120. Thecartridge 18 further includes an actuator mechanism 126 for moving thecontactor assembly 42 relatively with respect to the cartridge frame 38,and a travel sensor 128.

FIG. 7 illustrates the actuator mechanism 126, travel sensor 128, and awafer holder 130 holding a wafer 76. A cylinder 132 is manufactured inthe backing plate 120. The cylinder 132 has an outer surface 134 and anupper surface 138. A ring-shaped sliding piston 140 is inserted into thecylinder 132. A lower surface of the piston 140 is attached to thesupport structure 80. A fixed ring-shaped piston 136 is inserted intothe center of the piston 140. An upper surface of the fixed ring-shapedpiston 136 is attached to the backing plate 120. The support structure80 is thus connected through the piston 140, fixed ring-shaped piston136, and cylinder 132 of the actuator mechanism 126 to the backing plate120. By locating the actuator mechanism 126 between the backing plate120 and the support structure 80, the actuator mechanism 126 can movethe contactor assembly 42 relatively with respect to the backing plate120. A fluid passage 142 is manufactured in the backing plate 120. Thefluid passage 142 extends from an external surface of the backing plate120 to a location above an upper surface of the piston 140. A fluid line144 is connected to the fluid passage 142. Pressurized air or a vacuumpressure can be provided through the fluid line 144 and fluid passage142 to an upper surface of the piston 140.

The travel sensor 128 has an outer portion 146 attached to the supportstructure 80, and an inner portion 148 attached to the backing plate120. Relative movement between the outer portion 146 and the innerportion 148 results in a change of inductance (or capacitance) betweenthe outer portion 146 and the inner portion 148. The inductance (orcapacitance) can be measured to provide an indication of how far theouter portion 146 travels with respect to the inner portion 148. Theouter portion 146 fits within a circular opening in the backing plate,and the outer portion 146 additionally serves as a guide for movement ofthe contactor assembly 42 relative to the backing plate 120.

The wafer holder 130 forms part of the probing subassembly 16illustrated in FIGS. 1 and 2. The wafer holder 130 is mounted formovement in horizontal x- and y-directions and movement in a verticalz-direction to the prober base portion 26 of FIGS. 1 and 2.

As illustrated in FIG. 8, the wafer holder 130 with the wafer 76 thereonis moved in x- and y-directions until the wafer 76 is directly below thecontactor board 50. The wafer holder 130 is then moved verticallyupwardly in a z-direction towards the contactor board 50. Each one ofthe terminals 72 is aligned with a respective one of the contacts on thewafer 76. The terminals 72, however, do not at this stage touch thecontacts on the wafer 76.

As shown in FIG. 9, the actuator mechanism 126 is used to bring theterminals 72 into contact with the contacts on the wafer 76. Pressurizedair is provided though the fluid line 144 and the fluid passage 142 intoa volume defined by the surfaces 134 and 138 of the cylinder 132, anouter surface of the fixed ring-shaped piston 136, and an upper surfaceof the piston 140. The pressurized air acts on the upper surface of thepiston 140 so that the piston 140 is moved downward relative to thebacking plate 120. The piston 140 also moves the contactor assembly 42downward until the terminals 72 come into contact with the contacts onthe wafer 76. The terminals 72 are resiliently depressible againstspring forces of the pins that they form part of. The spring forcesjointly serve to counteract a force created by the pressure on thepiston 140.

FIG. 10 shows the force that is created by the piston 140. No force actson the terminals in FIGS. 7 and 8. In FIG. 9, the force is increasedfrom zero to a predetermined force. This predetermined force can becalculated by multiplying the pressure and the area of the upper surfaceof the piston 140. The forces created by the terminals 72 are highlycontrollable because the pressure is highly controllable. Thepredetermined maximum force can easily be modified from one applicationto another. When the forces are applied by the terminals 72, electricsignals, power, and ground are provided through the terminals 72 to andfrom the wafer 76. Integrated circuits on the wafer 76 are therebytested. Once testing is completed, the pressure is relieved so that theforces exercised by the terminals 72 are again reduced to zero. Anegative pressure is then applied, which moves the contactor assembly 42away from the wafer 76 into the position shown in FIG. 8. The wafer 76is then removed by the wafer holder 130 and the wafer 76 is replacedwith another wafer on the wafer holder 130.

It will be appreciated that the order and speed of moving the waferholder 130 relative to the contactor board 50 actuating the actuatormechanism 126 to bring the terminals 72 into contact with the contactsof the wafer 76 can be varied. Differing contact algorithms can be usedto move the wafer holder 130 and actuate the actuator mechanism 126 toachieve optimal contact (e.g., good electrical contact, least paddamage, etc.) for different types of wafers.

The travel sensor 128 allows the pressure of the piston 140 to be set sothat the piston 140 is roughly in the middle of its stroke when itcontacts the wafer 76. Wafers having differing contactor technologiesand/or number of contact points may be used with the apparatus 10.Different contact technologies often require a different force per pinto ensure wafer contact, and may also have different contactor heights.A different total force may be required to be applied to the contactorto make good contact with the wafer 76. The travel sensor 128 can beused to measure the distance the piston 140 has extended the contactortowards the wafer 76 under test. Thus, wafers having these varying typesof contactors can be tested using the same apparatus 10.

FIG. 11 illustrates an alignment and locking mechanism 152 mounted tothe upper portion 34 of the frame 12 in FIGS. 1 and 2, and one of thealignment pins 40 mounted to the cartridge frame 38.

The alignment and locking mechanism 152 includes an outer sleeve 154, analignment piece 156, a piston 158, a fluid line 160, and a lockingactuator 162.

The alignment piece 156 has an alignment opening 164 formed therein. Thealignment opening 164 has a conical shape so that an upper horizontalcross-section thereof is larger than a lower cross-section thereof. Thealignment piece 156 is mounted to an upper end of the outer sleeve 154and extends downwardly into the outer sleeve 154.

The piston 158 is located within a lower portion of the outer sleeve 154and can slide up and down within the outer sleeve 154. A cavity 166 isdefined within the outer sleeve 154 and by a lower surface of the piston158. The fluid line 160 is connected to the cavity 166. Positive andnegative pressure can be provided through the fluid line 160 to thecavity 166. Positive pressure causes upward movement of the piston 158,and negative pressure causes the piston 158 to move down.

The locking actuator 162 has a plurality of spherical locking members168 and a locking actuator 170. The locking actuator 170 is mounted tothe piston 158 so that it can move vertically up and down together withthe piston 158. The locking actuator 170 has an internal surface 172that makes contact with the spherical locking members 168. The surface172 is conical so that movement of the locking actuator 170 betweenraised and lowered positions causes corresponding movement of thespherical locking members 168 toward and away from one another.

The formation 40 includes a positioning pin 174 with a recessedformation 176 formed at a location distant from an end of thepositioning pin 174. The cartridge frame 38 is moved so that thepositioning pin 174 is roughly located over the alignment opening 164.When the cartridge frame 38 is lowered into the position shown in FIG.11, an end of the slightly misaligned positioning pin 174 can slide on asurface of the alignment opening 164 so that a center line of thepositioning pin 174 moves towards a center line of the alignment opening164. The piston 158 and the locking actuator 162 are in a loweredposition to allow for movement of a larger end of the positioning pin174 through an opening defined by the spherical locking members 168.

FIG. 12 illustrates the components of FIG. 11 after the formation 40 islowered all the way and engaged with the alignment and locking mechanism152. A conical surface on the formation 40 contacts the conical surfaceof the alignment opening 164, thereby further promoting correctalignment of the center lines of the positioning pin 174 and thealignment opening 164. The recessed formation 176 on the positioning pin174 is now at the same elevation as the spherical locking members 168.The piston 158 and the locking actuator 170 are elevated so that thespherical locking members 168 engage with the recessed formation 176.The positioning pin 174 is thereby engaged with the spherical lockingmembers 168 of the alignment and locking mechanism 152.

The positioning pin 174 can be released from the alignment and lockingmechanism 152 by first lowering the piston 158 so that the sphericallocking members 168 disengage from the recessed formation 176, and thenlifting the cartridge frame 38 together with the positioning pin 174 outof the alignment opening 164. It may from time to time be required thata cartridge 18 be temporarily removed for purposes of maintenance orreconfiguration, or be replaced with another cartridge. The formation 40and the alignment and locking mechanism 152 allow for quick removal andreplacement of cartridges.

FIG. 3 illustrates one and a piece of the alignment pins 40. Only pieceof the cartridge 18 is illustrated in FIG. 3 and the entire cartridge isin fact symmetrical about the section through one of the alignment pins40. The other piece of the sectioned formation 40 and another one of theformations are not shown. There are thus a total of three of thealignment pins 40 respectively at corners of a triangle. Each one of thealignment pins 40 engages with a corresponding alignment and lockingmechanism 152. The three alignment and locking mechanisms 152 are allsimultaneously and remotely actuable from a common pressure sourceconnected to corresponding fluid lines 160, to cause simultaneousengagement or disengagement of all three locking alignment pins 40.

As previously mentioned, with reference to FIGS. 1 and 2, the test head20 can be moved to the position shown in FIG. 2 for purposes ofmaintenance to the cartridge 18. The cartridge 18 can also be replacedas discussed with reference to FIGS. 11 and 12. Following maintenanceand/or replacement of the cartridge 18, the test head 20 is pivoted ontothe cartridge into the position shown in FIG. 1.

FIG. 13 illustrates portions of the test head and cartridge 18 after thetest head 20 is moved down onto the cartridge 18, i.e., from theposition shown in FIG. 2 into the position shown in FIG. 1. The testhead 20 has a second connector set 180 and an engager 182 mounted to thetest head frame portion 30 of the frame 12 of FIG. 1. The secondconnector set 180 is initially disengaged from one of the firstconnector sets 44 of the cartridge 18.

The first connector set 44 includes a connector block support piece 184,a first connector module 186, and a first engagement component 188.

The first connector module 186 includes a first connector block 190 anda plurality of septa 192. The septa 192 are held in a side-by-siderelationship by the first connector block 190. FIG. 14 illustrates oneof the septa 192 in more detail. A plurality of conductors is formedbehind one another into the paper against each septum 192. Eachconductor includes a terminal 196 at a lower edge of the septum 192, acontact 198 at an upper edge of the septum 192, and an electricallyconductive lead 200 interconnecting the terminal 196 with the contact198.

Referring again to FIG. 13, a number of the flexible attachments 46 areattached through respective connectors 202 to the terminals 196 of FIG.14. The septa 192 provide for a dense arrangement of the terminals 196and contacts 198 held by the first connector block 190.

The first connector module 186 is inserted into the connector blocksupport piece 184 with the first connector block 190 contacting an innerportion of the connector block support piece 184. The first connectormodule 186 is then secured to the connector block support piece 184 byreleasable means so as to again allow for removal of the first connectormodule 186 from the connector block support piece 184.

The first engagement component 188 has inner and outer portions 204 and206 respectively. The inner portion 204 is mounted to an outer portionof the connector block support piece 184 for pivotal movement about ahorizontal axis 208. A spring 210 biases the first engagement component188 in a counter-clockwise direction 212. The outer portion 206 has aspherical inner engagement surface 214 and a groove 216 as formed intothe engagement surface 214.

A slider pin 218 is secured to and extends vertically upwardly from oneof the upper support pieces 122 of the cartridge frame 38. Acomplementary slider opening 220 is formed vertically through theconnector block support piece 184. The slider opening 220 is positionedover the slider pin 218, and the first connector set 44 is moved downuntil the connector block support piece 184 rests on the upper supportpiece 122. The first connector set 44 is thereby held by the slider pin218 of the cartridge frame 38 and prevented from movement in horizontalx- and y-directions. The first connector set 44 can still be removedfrom the cartridge frame 38 by lifting the first connector set 44 out ofthe slider pin 218, for purposes of maintenance or reconfiguration.

The second connector set 180 includes a subframe 222, a second connectormodule 224, a cylinder 226, a piston 228, a rod 230, a spherical engager232, a connecting piece 234, and first and second supply lines 236 and238 respectively.

The subframe 222 is mounted to the test head frame portion 30. Thesecond connector set 180 is mounted through the subframe 222 to the testhead frame portion 30. The second connector set 180 has a secondconnector block 240 and a plurality of printed circuit boards 242mounted in a side-by-side relationship to the second connector block240. Each one of the printed circuit boards 242 has a respectivesubstrate, terminals on a lower edge of the substrate, contacts at anupper edge of the substrate, and electrically conductive traces, eachconnecting a respective terminal with a respective contact. The secondconnector block 240 is releasably held within the subframe 222 andsecured to the subframe 222 with releasable means.

The cylinder 226 is secured to the subframe 222. The piston 228 islocated within the cylinder 226 and is movable in vertically upward anddownward directions within the cylinder 226. First and second cavitiesare defined within the cylinder 226 respectively above and below thepiston 228, and the first and second supply lines 236 and 238 areconnected to the first and second cavities, respectively.

An upper end of the rod 230 is secured to a piston 228. The rod 230extends downwardly from the piston 228 through an opening in a base ofthe cylinder 226. The spherical engager 232 is secured via theconnecting piece 234 to a lower end of the rod 230. The connecting piece234 has a smaller diameter than either the rod 230 or the sphericalengager 232.

The engager 182 includes a plate 246 that is mounted to the subframe 222for pivotal movement about a horizontal axis 248, an actuator assembly201, and a link mechanism 252 connecting the plate 246 to the actuatorassembly 201. The actuator assembly 201 includes an actuator 250, aconnecting rod 253, an actuator pivot 251, and a rod pivot 255.

As previously mentioned, the second connector set 180 is initiallydisengaged from the first connector set 44. The second connector module224 is thus disengaged from the first connector module 186 and thespherical engager 232 is also disengaged from the first engagementcomponent 188. Pressurized air is provided through the first supply line236 while air is vented from the second supply line 238, so that thepiston 228 moves in a downward direction within the cylinder 226.Downward movement of the piston 228 extends the rod 230 further out ofthe cylinder 226 and moves the spherical engager 232 closer to thecartridge 18.

As illustrated in FIG. 15, the actuator assembly 201 is operated so thatthe link mechanism 252 moves the plate 246 in a counterclockwisedirection 254. The plate 246 comes into contact with an outer surface256 of the first engagement component 188. Further movement of the plate246 rotates the first engagement component 188 in a clockwise direction258 and in a camming action. A fork defined by the groove 216 moves overthe connecting piece 234, and the engagement surface 214 moves into aposition over at the spherical engager 232.

As illustrated in FIG. 16, pressurized air is provided through thesecond supply line 238, and air is vented through the first supply line236 so that the piston 228 moves in a vertically upward direction. Therod 230 retracts in an upward direction into the cylinder 226. An uppersurface of the spherical engager 232 engages with the engagement surface214 and moves the first engagement component 188 towards the cylinder226. The first connector set 44 lifts off the upper support piece 122 ofthe cartridge frame 38, and the connector block support piece 184 slidesup the slider pin 218.

The pressurized air provided through the second supply line 238 alsocreates a force that is sufficiently large to overcome an insertionforce required to mate the first connector module 186 with the secondconnector module 224. Each one of the septa 192 enters into a gapbetween two of the printed circuit boards 242. Gaps between the contacts198 on the septa 192 and the gaps between the printed circuit boards 242are sufficiently small so that an interference fit is required to insertthe septa 192 between the printed circuit boards 242. Once the insertionforce is overcome and the septa 192 are located between the printedcircuit boards 242, each one of the contacts 198 is located against acorresponding terminal on a lower edge of one of the printed circuitboards 242.

The pressurized air provided through the second supply line 238 can beremoved after the first and second connector modules 186 and 224 aremated. The first and second connector modules 186 and 224 can bedisengaged from one another by providing pressurized air through thefirst supply line 236 so that the first connector set 44 moves into theposition as shown in FIG. 15. The actuator assembly 201 is then operatedand the plate 246 moves into the position shown in FIG. 13. The spring210 biases the first engagement component 188 in the counterclockwisedirection 212 away from the spherical engager 232. The rod 230 is thentypically again retracted into the cylinder 226.

As illustrated in FIG. 17, cartridge 38 has four of the upper supportpieces 122, and a respective pair of the upper support pieces 122carries a respective column of the first connector sets 44. The columnsare located next to one another so that a respective pair of the firstconnector sets 44 is in a respective row. There can be a total of 16rows in each of the two columns, thus potentially forming an array of 32of the first connector sets 44.

Each one of the first connector sets 44 is symmetrical on the left andthe right. The connector block support piece 184 entirely surrounds thefirst connector module 186, and two slider openings (220 in FIG. 13) areprovided at opposing ends of the connector block support piece 184.Slider pins 218 are provided on all four of the upper support pieces122, and each respective connector block support piece 184 has twoslider openings 220 respectively located over two of the slider pins218.

As shown in FIG. 18, an array of second connector modules 224 isprovided, matching the array of first connector modules 186 of FIG. 17.Two spherical engagers 232 are located on opposing sides of each one ofthe second connector modules 224. In use, a respective pair of sphericalengagers 232 is used to engage one of the first connector modules 186with one of the second connector modules 224 independently of the otherconnector modules. One of the first connector modules 186 is engagedwith one of the second connector modules 224, where after another one ofthe first connector modules 186 is engaged with another one of thesecond connector modules 224, etc. By staggering the engagement of arespective first connector module 186 with a respective second connectormodule 224, forces on the subframe 222 and other pieces of the frame 12of FIG. 1 can be kept within their design parameters.

Each one of the plates 246 is located adjacent a plurality of thespherical engagers 232. Movement of a respective one of the plates 246causes the respective plate 246 to contact an simultaneously pivot aplurality of the first engagement components 188 of FIG. 13 over aplurality of respective ones of the spherical engagers 232.

Referring to FIGS. 18 and 19 in combination, each one of the secondconnector modules 224 is mounted to respective pattern generator,driver, and power boards, 260, 262, and 264 respectively, each residingin a respective slot of a base structure 266. As specifically shown inFIG. 19, access can be gained to the boards 260, 262, and 264 byrotating the thermal system frame portion 28 together with the test headframe portion 30 an additional 135 degrees counterclockwise to the leftwhen compared to FIG. 2, and then rotating the test head frame portion30 relative to the thermal system frame portion 28 90 degrees clockwiseto the right. The thermal system 24 is then positioned on the ground andthe test head 20 in a vertical orientation. The boards 260, 262, and 264are all accessible from the left within the test head 20 because thetest head 20 and the thermal system 24 have been separated from oneanother. The boards 260, 262, and 264 that reside in the slots of thebase structure 266 are then removable, replaceable, and other boards canbe added, for purposes of reconfiguration.

Each one of the slots can only carry one particular type of board 260,262, or 264. The base structure 266 is configurable so that slots areconfigurable to allow for more or fewer of a particular board, or tomodify the locations of particular boards. Once the slots are inserted,they are typically not replaced over the life of the apparatus 10. Thenumber of boards 260, 262, and 264 that are used can still be configuredfrom one application to the next. FIG. 20 illustrates an example of alayout of slots in the test head 20. The particular layout of slots ofFIG. 20 allows for the use of two pattern generator boards 260, one onthe left and one on the right; six driver boards 262, three on the leftand three on the right; and 24 power boards 264, twelve on the left andtwelve on the right.

After the boards 260, 262, and 264 are inserted into the slots asdiscussed with reference to FIGS. 19 and 20, the apparatus is firstmoved into the configuration illustrated in FIG. 2 with the thermalsystem 24 above the test head 20, and then into the configurationillustrated in FIG. 1, with the components of the test head 20electrically connected to the components of the cartridge 18 in FIG. 2.

Referring specifically to FIG. 1, what should be noted is that thethermal system 24 does not rest on the test head 20. Any vibrationscaused by components of the thermal system 24 can thus not be directlytransferred to the test head 20. The test head 20 and the thermal system24 are held in the relative orientation shown in FIG. 1 with the thermalsystem 24 above the test head 20 by the thermal system frame portion 28and the test head frame portion 30, respectively, of the frame 12. Theframe 12 is relatively heavy and has a rigid construction, andeffectively dampens any vibrations created by components of the thermalsystem 24. The vibrations substantially do not reach the components ofthe test head 20.

FIG. 21 illustrates how the thermal system 24 cools components of thetest head 20. FIG. 21 is a partial cross-sectional view parallel to aplane of one of the boards 260, 262, and 264 of FIG. 20, and shows oneof the driver boards 262 and one of the power boards 264 inserted intotheir respective slots of the base structure 266 of the test head 20.The test head 20 further has two manifold panels 268 mounted on opposingsides and at upper portions of the base structure 266. The basestructure 266 has openings between the slots that allow for air to flowfrom the manifold panels 268 inward to the boards 262 and 264, and thenfrom the boards 262 and 264 to an upper end exhaust 270.

The thermal system 24 includes an outer shell 272, four recirculationfans 274 (only two of the recirculation fans 274 are shown in FIG. 21;the other two recirculation fans are located behind the recirculationfans 274 that are shown in FIG. 21), and two heat exchangers 276. Theair leaving the upper end exhaust 270 is sucked through therecirculation fans 274 into the outer shell 272. Recirculation fans 274then force the air through the heat exchangers 276, whereafter the airenters through upper end inlets 278 defined by the manifold panels 268.By recirculating the air, heat convects from the boards 262 and 264 tothe heat exchangers 276. As is commonly known, each heat exchanger 276includes a plurality of fins 280 and tubing 282 connecting the fins 280to one another. A cooling fluid such as liquid water is pumped throughthe tubing 282. The heat convects to the fins 280. The heat conductsfrom the fins 280 to the tubing 282. The heat then convects from thetubing 282 to the water and is pumped away.

What should be noted is that there is no physical contact between anycomponents of the thermal system 24 and any components of the test head20. Only a small gap 284 is defined between the outer shell 272 and themanifold panel 268. A seal is typically located in the gap 284, and ismade of a compliant material so that any vibrations transferred by thefan 274 to the outer shell 272 do not transfer to the manifold panels268. Guide panels 286 form part of the thermal system 24, and serve toprevent the air from entering the test head 20 before first passingthrough the fans 274 and the heat exchangers 276.

FIG. 22 illustrates software and hardware components of the apparatus 10of FIG. 1 that cooperate and that are matched to one another forfanning-out and fanning-in of electric signals, power, and ground. Zonesare defined, wherein each zone includes one pattern generator board 260,one or more driver boards 262, and one or more power boards 264connected to one another. Each board 260, 262, and 264 has a number ofresources or channels. In particular, a driver board 262 has a number ofinput/output channels, and the power board 264 has a number of powerchannels. The number of boards 260, 262, and 264 and the way that theyare connected to one another are configurable, depending on therequirements of integrated circuits of devices 300 and the layout of thedevices 300 of the wafer 76.

An interconnection scheme 302 connects the driver and power boards 262and 264 to contacts on the devices 300. The interconnection scheme 302includes the electrical paths formed by conductors within the cartridge18 of FIG. 3. The interconnection scheme 302 is also configurable, aswill be appreciated from the foregoing description of the cartridge 18.The boards 260, 262, and 264 and the interconnection scheme 302 arehereinafter jointly referred to as a tester system 304.

A local controller 306 is used to provide test instructions to thetester system 304 and is then used to upload and process test resultsfrom the tester system 304. The local controller 306 has memory and,stored in the memory, are a test program 308, a configuration file 310,a test application 312, a test results file 314, a processingapplication 316, and a test report 318.

Reference should now be made to FIGS. 22 and 23 in combination. The testprogram 308 has a series of instructions written by a test programmer totest one of the devices 300 (step 400). The following is an extract ofsuch a program:

setdps (“v NORMAL 1”, “Vcc”, 3.0 V, 0.0 V, 11.0 V);

setdps (“v NORMAL 1”, “Vcd”, 4 V, 0.0 V, 11.0 V);

setsps (“v NORMAL 1”, “Vio”, 0 V, 3.3 V);

setsps (“v NORMAL 1”, “Vclk”, 0 V, 3.3 V);

setsps (“v NORMAL 1”, “Vcs”, 0 V, 3.3 V);

setpps (“v NORMAL 1”, “Term 1”, 1.0);

settps (“v NORMAL 1”, “Term 2”, 1.0);

setthps (“v NORMAL 1”, “CompH”, 1.5);

setthps (“v NORMAL 1”, “CompL”, 0.9).

The test application 312 utilizes both of the test program 308 and datafrom the configuration file 310 and data from the test results file 314to provide instructions to the boards 260, 262, and 264 (step 402). Theboards 260, 262, and 264 then provide electric signals, power, or groundthrough respective conductors of the interconnection scheme 302 (step404). The configuration file 310 has data representing a relationshipbetween the channels of the boards 260, 262, and 264 and the contacts ofthe devices 300. The configuration file 310 will be different from oneconfiguration assembly to another configuration assembly of the testersystem 304. The configuration file 310 thus represents how theinstructions of the test program 308 are fanned out through the testersystem 304 to the devices 300. Each device 300 is tested with the sametest program 308 (step 406), although the voltage and signal levels maybe modified based upon the test result file 314.

The following table is an extract of the configuration file 310 withfield names listed at the top of each column:

PWR ZONE SLOT CHANNEL RAB MODULE CHANNEL CONN PAD TERM COMMON NUMBERNUMBER TYPE NUMBER NUMBER NUMBER COLUMN ROW TYPE LABEL LABEL KEY MASK 229 HVOL 1 1 0 5 16 D CE 0 0 0 2 22 DRV_CS −1 −1 0 1 20 D OE CS_0 0 0 1 6DRV_CS −1 −1 0 37 15 D OE CS_0 0 0 1 6 DRV_UCLK −1 −1 0 35 15 D DQ1 A_00 0 2 22 DRV_UCLK −1 −1 0 7 20 D DQ1 A_0 0 0 2 22 DRV_UCLK −1 −1 1 20 25D DQ1 B_1 0 0 2 22 DRV_IO −1 −1 1 2 21 D DQ7 I/O_1 0 0 1 6 DRV_UCLK −1−1 1 15 10 D DQ1 B_1 0 0 2 22 DRV_CS −1 −1 1 3 21 D OE CS_1 0 0 1 6DRV_CS −1 −1 1 32 14 D OE CS_1 0 0 1 6 DRV_UCLK −1 −1 1 15 2 D DQ1 B_1 00 1 6 DRV_UCLK −1 −1 1 17 14 D DQ1 B_1 0 0 1 6 DRV_IO −1 −1 1 37 13 DDQ7 I/O_1 0 0 1 6 DRV_CS −1 −1 1 28 6 D OE CS_1 0 0 1 6 DRV_UCLK −1 −1 116 14 D DQ1 B_1 0 0 2 22 DRV_UCLK −1 −1 1 6 25 D DQ1 A_1 0 0 2 22 DRV_CS−1 −1 1 10 17 D OE CS_1 0 0 2 22 DRV_CS −1 −1 1 11 21 D OE CS_1 0 0 2 22DRV_UCLK −1 −1 1 21 21 D DQ1 B_1 0 0 1 6 DRV_UCLK −1 −1 1 16 10 D DQ1B_1 0 0 2 22 DRV_CS −1 −1 1 2 21 D OE CS_1 0 0 2 22 DRV_UCLK −1 −1 1 2317 D DQ1 B_1 0 0 2 22 DRV_CS −1 −1 1 1 21 D OE CS_1 0 0 2 22 DRV_CS −1−1 1 9 17 D OE CS_1 0 0 1 6 DRV_UCLK −1 −1 1 16 2 D DQ1 B_1 0 0 1 6DRV_CS −1 −1 1 27 3 D OE CS_1 0 0 1 6 DRV_UCLK −1 −1 1 36 14 D DQ1 A_1 00 2 22 DRV_CS −1 −1 1 16 32 D OE CS_1 0 0 1 6 DRV_UCLK −1 −1 1 18 6 DDQ1 B_1 0 0 1 6 DRV_CS −1 −1 1 34 10 D OE CS_1 0 0 2 22 DRV_UCLK −1 −1 16 21 D DQ1 A_1 0 0 1 6 DRV_CS −1 −1 1 31 14 D OE CS_1 0 0 1 6 DRV_UCLK−1 −1 1 32 6 D DQ1 A_1 0 0 2 22 DRV_UCLK −1 −1 1 8 25 D DQ1 A_1 0 0

The fields at the top of the columns of the table above stand for thefollowing:

ZONE NUMBER: index to indicate membership to a pattern zone, determinedby pattern generator board 260.

SLOT NUMBER: location of a driver or power board 262 or 264.

CHANNEL TYPE: type of hardware resource to be used.

RAB NUMBER: index of reference and acquisition module on the power board264, or −1 if not applicable.

PWR MODULE NUMBER: power module on power board 264.

CHANNEL NUMBER: resource index of given board 262 or 264.

COLUMN, ROW: position of the device 266 on the wafer (or testboard).

CONN TYPE: connection type; D for device, or T for termination; whethera resource influences a device directly, or provides auxiliaryelectrical characteristics to the test assembly.

PAD LABEL: designator for the terminal 72 or pin 68 that the resource isconnected to; this label is then used for programming purposes.

TERM LABEL: option label for a termination pin.

COMMON KEY: option sort key.

MASK: field to determine whether a device should be tested or not.

Some resources are provided separately to each of the devices 300. Forexample, there may be a total of 600 of the devices 300, and each devicemay require a separate input/output line connected through theinterconnection scheme 302. Other resources may be shared in order toreduce the number of electrical paths that are provided through theinterconnection scheme 302. For example, a single input/output line 320can be provided through the interconnection scheme 302, and at the lastlevel within the interconnection scheme 302 be fanned to a set (or all)of the devices 300. An input/output signal is thus provided to all thedevices 300 of the set. A chip select line 322 can be accessed to selecta subset of the devices of the set to which the input/output line 320 isconnected. Unique chip select line combinations are then grouped intochip select states.

FIGS. 24A and 24B illustrate the data structure of the configurationfile 310 (“cartconf”). The configuration file 310 includes both a waferrequirement data structure (wafer_reqs) and a shared resources map(cs_map) representing the chip select states. Descriptions of therespective fields and what the fields represent are described in FIGS.24A and 24B.

Again referring to FIGS. 22 and 23, a response from each one of thedevices 300 is provided through the interconnection scheme 302 andstored in memory of the driver and power boards 262 and 264 (step 408).The system software uploads the responses from the driver and powerboards 262 and 264 into the test results file 314 (step 410). The testresults file 314 has raw data wherein the test results of all thedevices 300 are collated. The test results file 314 is provided to aprocessing application 316. The processing application 316 utilizes theconfiguration file 310 to interpret the test results file 314 in such amanner that the test results of individual ones of the devices 300 areextracted from the test results file 314 (step 412). The processingapplication 316 then publishes the test report 318 (step 414). The testreport 318 is typically a two-dimensional map on a computer screen withcells representing the devices 300, wherein functioning and defectivedevices are shown in different colors. The test results file 314 is alsoto be used by the test application 312 to modify the instructionsprovided to boards 260, 262 and 264.

FIG. 25 illustrates a software assembly application 420 that is used forconstructing the configuration file 312 of FIG. 19. The application 420includes a plurality of net files 422, an input module 424, and anassembly module 426. The net files 422 each represent a scheme ofcurrent passing through conductors of a respective electricalsubassembly. For example, the net file 422A is a pattern generator boardnet file representing the flow of current through one of the patterngenerator boards 260 of FIG. 19. Similarly, the driver board net file422B and power board net file 422C respectively represent flow ofcurrent through conductors through one of the driver boards 262 and oneof the power boards 264. The interconnection scheme 302 also hasmultiple components, and a respective net file 422D or 422E representsflow of current through a respective component of the interconnectionscheme 302.

Referring now to FIGS. 25 and 26 in combination, the net files 422 arefirst stored in memory of a computer system on which the softwareassembly application 418 resides (step 450). The input module has aninterface with a list of the components that can make up the testersystem 304. The list includes one pattern generator board, one driverboard, one power board, and one type of each component that can make upthe interconnection scheme 302. The input module 424 also allows anoperator to select how many of the components on the list are used toassemble the tester system 304, and how the components are connected toone another. For example, the operator can select two pattern generatorboards and three driver boards, one of the driver boards being connectedto one of the pattern generator boards and the other two driver boardsbeing connected to the other pattern generator board (step 452).

The assembly module 426 then uses the input provided by the operator viathe input module 424 and the net files 422 to assemble the configurationfile 310. In the given example, the assembly module 426 will constructthe configuration file 310 so that it has data representing two patterngenerator net files 422A and three driver board net files 422B, with onedriver board net file 422B being associated with one pattern generatorboard net file 422A and the other two pattern generator net files 422Bbeing associated with the other pattern generator board net file 422A(step 454). The configuration file 310 can then be transferred from thecomputer system on which the software assembler application 420 residesto the local controller 306 of FIG. 22.

FIG. 27 illustrates some of the components hereinbefore described andsome additional components of the apparatus 10. The componentshereinbefore described include the cartridge 18 that has the contactorassembly 42, the flexible attachments 46, two of the power boards 264,one of the driver boards 262, one of the pattern generator boards 260,and the local controller 306. Two types of power boards 264V and 264Care used, for high voltage and high current respectively. Each powerboard 264V or 264C has eight logical groups of 64 channels, andtherefore 512 channels in total. The high-voltage power board 264V canprovide a voltage output of 0.5 V to 12 V at a current of at least 200mA for each channel. The high-current power board 264C can provide anoutput of 0.1 V to 5 V at a current of at least 500 mA. The locations ofthe boards 260, 262, and 264 have been described with reference to FIG.20.

Each one of the power boards 264V or 264C is connected to the contactorassembly 42 through four dedicated power flexible attachments 46P. Thedriver board 262 is connected to the contactor assembly 42 throughdedicated signal flexible attachments 46S. The flexible attachments 46have been described with reference to FIG. 3. The flexible attachments46 connecting at site 92 at the distribution board 48 also providealternating current (AC) ground from the contactor assembly 42 to theboards 262 and 264.

The apparatus 10 further includes a ground plate 460 and a Bussedlow-voltage differential signaling (LVDS) backplane 462 mounted withinthe test head 20. The power boards 264V and 264C and the driver board262 each have two direct current (DC) connection pins 508, asillustrated in FIG. 18, that connect to the ground plate 460. The DCpins 508 also pass through the ground plate 460 and connect to the blocksupport piece 184, shown in FIG. 17. DC ground cables 464 connect theblock support piece 184 to the signal distributor board 48, shown inFIG. 4, at the DC connection site 461, illustrated in FIG. 6, andthereby provide a DC ground path from the boards 262 and 264, thecontactor assembly 42, and the wafer 76. FIG. 3 illustrates connectors466 to which the DC ground cables 464 are attached at the block supportpiece 184 of the cartridge 18.

The boards 260, 262, 264C, and 264V each have a connection that connectsrespective board to the Bussed LVDS backplane 462. A logical link isthereby provided between the boards 260, 262, 264C, and 264V, allowingthe boards to communicate with one another. It is also the Bussed LVDSbackplane 462 that provides the logical link between the boards 260,262, and 264 illustrated in FIG. 22.

The apparatus 10 further has a system control bay 470 that includes abulk die power supply 472V for high voltage, a bulk die power supply472C for high current, the local controller 306 described with referenceto FIG. 22, and a system controller 474. The bulk die power supply 472Vcan provide a voltage of 0.5 V to 13 V at 110 A, and the bulk die powersupply 472C can provide a voltage of 0.5 V to 7 V at 200 A. The bulk diepower supply 472V is connected through respective power cables 476 topower board(s) 264V. Similarly, the bulk die power supply 472C isconnected through respective power cables 476 to power board(s) 264C.

An Ethernet link 478 connects and networks the bulk die power supplies472V and 472C, the local controller 306, the system controller 474, andthe boards 260, 262, 264C, and 264V with one another. The localcontroller 306 controls the boards 260, 262, 264C, 264V, and 474 throughthe Ethernet link 478 and peripheral components of the apparatus 10.

FIG. 28 illustrates one of the power boards 264V or 264C and itsconnections to the ground plate 460, and power flexible attachments 46P.A board-level control and bulk power control 490 is connected to theEthernet link 478. A board power control 492 and calibration control 494are connected to the board-level control and bulk power control 490. Theboard-level control and bulk power control 490, device power timingsystem 500, and the calibration control 494 are connected to a referenceand measurement system 496 and provide a series of instructions to thereference and measurement system 496. The instructions have beendescribed with reference to FIG. 22 (the instructions that are providedby the board-level control and bulk power control 490, the device powertiming system 500, and calibration control 494 to the reference andmeasurement system 496 have, for purposes of explanation, been equatedto chords in a music score).

The pattern generator board 260 has a pattern generator power timing busthat is connected through the Bussed LVDS backplane to a device powertiming system 500. The device power timing system 500 is connected tothe reference and measurement system 496. The device power timing system500 provides both timing and instructions to the reference andmeasurement system 496 for purposes of carrying out the instructionsthat are provided from the board-level control and bulk power control490 and calibration control 494 (the functioning of the device powertiming system 500 has, for purposes of explanation, been equated to anorchestra conductor that provides both timing and instructions of whichchords are to be played). The reference and measurement system 496includes eight logical systems of 64 channels each, thus totaling 512channels. Inputs into the reference and measurement system includesignals from the pattern generator index bus, pattern generator clocks,calibration reference, and ground sense. The reference and measurementsystem 496 performs voltage readback and current readback. Output fromthe reference and measurement system 496 includes four voltagereferences and device power control through a device power control bus.Output from the reference and measurement system 496 thus includes logicfor purposes of controlling power.

The reference and measurement system 496 and board-level control andbulk power control 490 are connected to a device power output system502. A positive side of the bulk die power supply 472V or 472C is alsoconnected to the device power output system 502 through cable 476. Thedevice power output system 502 regulates the power from the bulk diepower supply 472V or 472C, utilizing the signal from the reference andmeasurement system 496 (the power provided by the bulk die power supply472V or 472C has, for purposes of explanation, been equated to power orair that is provided simultaneously to a number of music instruments inan orchestra). The device power output system 502 includes 16 sectionsof 32 channels, grouped into 8 logical groups, thus totaling 512channels. Each channel includes a Kelvin sense system, each systemincluding one force (+F) and one sense (+S) line, so that there are atotal of 1,024 pins and circuits. Input into the device power outputsystem 502 includes references, bulk power, control parameters fromboard-level control and bulk power control 490, and device power controlthrough the device power control bus. The device power output system 502also provides voltage and current readback to the reference andmeasurement system 496 and channel status information to the board-levelcontrol and bulk power control 490.

Four of the power flexible attachments 46P are connected to the devicepower output system 502. Each power flexible attachment 46P includes128+F lines, 128+S lines, AC ground, and ground sense.

Two ground sense traces from each power flexible attachment 46P, thustotaling eight traces, are connected to a board ground control system506. The board ground control system 506 averages eight measurementsfrom the ground sense traces, and provides the averaged result as anoutput to the reference and measurement system 496.

A ground pin 508 is connected to the ground plate 460 and the firstconnector sets 44. The ground pin 508 is connected to both the devicepower output system 502 and to a board power system 510. The board powersystem 510 has a separate 48 V input, and can provide, for example,outputs of 15 V, 5 V, 3.3 V, −3.3 V, and 1.2 V. The DC ground cables 464are connected to the block support piece 184. The negative side of thebulk die power supply 472V or 472C is also connected through the powercable 476 to the ground plate 460.

What should be noted is that separate paths are provided for AC groundand for DC ground. AC ground is provided through the flexibleattachments 46P that also deliver the power. The physical space betweenF+ power provision, the S+ line, and AC power ground in a power flexibleattachment 46P is extremely small, typically on the order of between0.002 and 0.010 inches. Such a small space allows for a substantialreduction in noise and an increase in speed, which is particularlyimportant for accurate measurement through the 512 sense lines and cleanpower delivery through the F+ lines. DC ground is provided through theDC ground cables 464. The AC and DC grounds have, for example,respective resistances of between 0.5 and 1.5 ohms and 0.003 and 0.015ohms.

FIG. 29 illustrates components of the device power output system 502 inmore detail. The device power output system 502 includes only a singleone of subsystem A. The subsystem B is replicated 512 times and is ineight groups of 64, and the 512 subsystems B are connected in parallelto the subsystem A. The subsystem C is replicated eight times, and theeight subsystems C are connected in parallel to the subsystem B.

Subsystem A includes die bulk power supply 472 and power cables 476which include an AC-to-DC conversion circuit comprising an inductor Iand a capacitor C1 connecting an output terminal of the inductor I toground and is controlled by board-level control and bulk power control490 and local controller 306 through 478. An input terminal of theinductor I is connected to the die bulk power supply 472V or 472C inFIG. 27. A stepped voltage cycle is provided to an input terminal of theinductor I. An amplitude and a period of the stepped voltage cyclealways remain constant, but an amount of time that the voltage is highduring a particular period can be modulated. The total amount of timethat the voltage is high can thus be modulated from a small percentageof the total time to a large percentage of the total time. The inductorI and capacitor C1 convert the voltage step to a DC voltage. The DCvoltage can thus also be modulated, depending on the percentage of timethat the voltage provided to the input terminal of the inductor I ishigh. The die bulk power supply 472V or 472C allows for a variablevoltage to be created per power board 264. The DC voltage can thus bemodulated, depending on the need to control power dissipation in thedevice power output system 502. The reference and measurement system 496allows for 16 different voltages to be created per group of 64 channels.Different voltages can be provided to different groups of 64 channels ata particular moment in time.

The DC voltage created by the subsystem B is provided through a force F+line through a power terminal 72P to a power contact 74P of a respectivedevice 300 (see also reference numerals 72 and 74 in FIG. 4). A senseline S+ is connected to the power terminal 72 or 56 and detects avoltage at the power terminal 72. The voltage detected by the sense lineS+ is provided through a resistor R2, an amplifier A3, and a resistor R1to control a MOSFET 1 located in the force line F+. The amplifier A3also receives at its positive terminal an input (Vref) through a switch594. The amplifier A3 is set so that the voltages provided at itspositive and negative terminals are combined to provide an outputvoltage to the MOSFET 1. The voltage Vrefout provides an input voltage,which is the desired voltage provided to the power terminal 72P, and thesense line S+ provides a feedback through the amplifier A3 to keep thevoltage provided to the MOSFET 1, and therefore the power terminal 72P,at a steady state. The amplifier A3 provides a voltage (Vrefout+V_(GS)),in this case 2.3 V, to the MOSFET 1 if the voltage provided by thesubsystem A is 1.5 V and the power terminal 72P requires a voltage of 1V. The MOSFET 1 dissipates heat equivalent to a difference between thevoltage provided by the subsystem A and the voltage on the force lineF+, multiplied by the current. For example, the voltage provided by thesubsystem A can be 1.5 V, and the force line F+ can provide a voltage of1 V. If the current is 1 A, the power dissipated by the MOSFET 1 is 0.5W. Should the voltage provided by the subsystem A always be a maximumof, for example, 12 V, the MOSFET 1 would have to dissipate 11 W. Thevariable power provided by the bulk die power supplies 472V and 472C inFIG. 27 thus substantially assist in reducing the amount of energy, andtherefore heat, dissipated by the MOSFET 1.

A resistor R3 is connected between the force and sense lines F+ and S+and resistively connects the F+ to the S+ of the amplifier A3. Theresistor R3 serves to control the amplifier A3 in case of a failure byholding the force and sense lines F+ and S+ to similar voltages. Theresistor R3 is thus just a safety device in case of contact failure.

The subsystem B also includes a circuit that automatically switchespower to the device 300 off upon the detection of an overcurrent, amongother things. The overcurrent detection and switching circuit includes aresistor R6 located after the MOSFET 1 in the force line F+. A voltageover the resistor R6 is linearly related to a current through the forceline F+. An amplifier A1 amplifies the voltage detected over theresistor R6. A comparitor A2 compares an output from the amplifier A1 toa current set point supplied by reference and measurement system 496. Anoutput from the comparitor A2 would be zero if the output from theamplifier A1 is the same as, or greater than, the current set point.

The output from the comparitor A2 provides an indication of anovercurrent or undercurrent through the resistor R6. The output from thecomparitor A2 is provided to a field programmable gate array (FPGA) 1.The FPGA 1 has logic that determines whether the over- or undercurrentis sufficient to switch subsystem B off. The FPGA 1 also provides for atiming delay before switching the current off, to allow for brief surgesin current without switching the current off. An output of the FPGA 1 isprovided to a switch 1 and a switch 2 594.

During normal operating conditions, i.e., when the current shouldcontinue to flow, the switch 1 is switched into its “off” position andthe switch 2 in its “A” position. A voltage of 15 V is provided througha resistor R5 to one terminal of the switch and to a MOSFET 2 locatedafter the resistor R6 in the force F+ line. During normal operatingconditions, the voltage provided through the resistor R5 maintains theMOSFET 2 in an “on” position, thereby allowing current to flow throughthe force line F+. Should an overcurrent be detected, the FPGA 1switches the switch 1 to its “on” position, thereby grounding thevoltage provided through the resistor R5, the MOSFET 2 will switch intoits “off” position and disconnect the current, and switch 2 is set tothe “B” position, shutting down the amplifier A3.

What should be noted is that each one of the 512 subsystems B has itsown overcurrent detection and switching circuit. The 512 overcurrent andswitching circuits allow for currents to one or more of 512 individualdevices to be switched off, while current to the other devices continuesto flow. Current measurement and voltage measurement can also be done ona per-device level, because each one of the subsystems B has arespective current measurement line (Imeas), and a respective voltagemeasurement line (Vmeas). The current measurement line Imeas isconnected to an output of the amplifier A1, and the voltage measurementline Vmeas is connected to the sense line S+. The current and voltagemeasurement lines Imeas and Vmeas allow for real-time measurement ofcurrent and voltage provided to the power terminal 72P. The subsystem Balso includes a switching circuit having a resistor R4 and a MOSFET 3.The resistor R4 is connected to the force line F+ after the MOSFET 2,and the MOSFET 3 is connected in series after the resistor R4. A testsignal (Test) can be provided to the MOSFET 3, thereby drawing currentthrough the force line F+ for self-testing.

A high-frequency response is required for the circuit that includes theresistors R1, R2, and the amplifier A3. For this purpose, a capacitor C3is provided in parallel with the integrated circuit of the device 300.The capacitor C3 is built into the support structure 80 shown in FIG. 4.The force line F+ should have a relatively low inductance to allow forproper functioning of the capacitor C3 and high-frequency response ofthe circuit, including the resistors R1 and R2 and the amplifier A3. Forthis purpose, the force line F+ includes two sets of parallel powerconductors 590 and 592, respectively. The subsystems A and B areconnected to a single substrate with the conductors 590 of the first setare traces that are formed on the substrate. The conductors 590 all havefirst ends that are connected to one another and second ends that areconnected to one another, so that middle sections of the conductors 590conduct current in parallel. The second ends of the conductors 590 areconnected to a common pin. The conductors 592 are in the form ofindividual electric lines in a respective power flexible connection 46P.First ends of the conductors 592 are connected to one another and secondends of the conductors 592 are connected to one another, so that middlesections of the conductors 592 conduct the current received from theconductors 590, in parallel. The second ends of the conductors 592 areall connected to one power terminal 72P.

The distribution board 48 has two ground sense contacts at eachinterface 92. Ground sense terminals at each interface 92 connect to theground sense contacts 74G. Eight ground sense lines are provided to agrounding modulation circuit, including an amplifier A4 and a filter201. The voltage detected at the ground sense contact 74G is added bythe ground modulation circuit to a variable input voltage (Vrefin).Ideally, the voltage detected at the ground sense contact 74G is 0 V, inwhich case the voltage variable Vrefin would be equal to the voltageVrefout. If the voltage detected at the ground sense contact 74G is notzero, for example, it is 0.1 V, then Vrefout would be driven to 1.1 V(Vrefin+0.1 V). The voltage provided to the negative terminal of theamplifier A3 would then also be 1.1 V, and the voltage provided to thepower terminal 74P would be 1.1 V.

FIG. 30 illustrates one channel of the driver board 262 shown in FIGS.22 and 27. The same signal illustrated in FIG. 30 is replicated for eachof multiple channels of the driver board 262.

Also illustrated in FIG. 30 are multiple ones of the devices 300 andtheir respective ground sense contacts 72G. Voltages detected byrespective ground sense terminals on the ground sense contacts 74G (or72G) are averaged and provided to a filter 700. Under normal operatingconditions, the voltage provided to the filter 700 would be 0 V. Theremay sometimes be a small deviation from 0 V, for example, 0.1 V. The 0.1V is provided by the filter 700 to a positive terminal of an amplifierA4. A negative terminal of the amplifier A4 is then also driven to 0.1V. One resistor R9 is connected between the negative terminal and anoutput of the amplifier A4. A resistor R10, having the same resistanceas the resistor R9, is also connected to the negative terminal of theamplifier A4. A 10 V voltage source 702 is connected over the resistorsR9 and R10. Two terminals of the voltage source 702 are then 5 V aboveand 5 V below the voltage at the negative terminal of the amplifier A4,and thus at −4.9 V and 5.1 V, respectively.

The terminals of the 10 V voltage source 702 are connected to respectiveterminals R+ and R− of a digital-to-analog converter (DAC) 704. The DAC704 also has output terminals, and has the ability to switch each outputterminal to a voltage between −4.9 V and 5.1 V.

A microprocessor bus 705 is connected to the DAC 704. Informationrepresenting desired high and low voltages can be loaded from themicroprocessor bus 705 into the DAC 704. The DAC 704 can, for example,be programmed with a high voltage of 3 V and a low voltage of 2 V.Because the voltage provided to the positive terminal of the amplifierA4 is at 0.1 V, the output terminals of the DAC are, in this example,held at 3.1 V and 2.1 V, respectively.

The output terminals of the DAC are connected to high-voltage andlow-voltage (VH and VL) terminals of a voltage switch 706. The patterngenerator board 260 illustrated in FIGS. 22 and 27 provides a signalsource 708 to a signal terminal of the voltage switch 706. The voltageswitch is a bus switch in the present example, having a 5 V power supplyvoltage. The signal source 708 switches between alternating true andfalse states. In a true state, a first terminal of the switch 706connected to the high-voltage VH is connected to an output of the switch706, and in a false state, the terminal connected to the low-voltage VLis connected to the output of the switch 706. The output of the switch706 thus switches between 3.1 V and 2.1 V in response to the signalsource 708.

A damping circuit, including a resistor R11 and a capacitor C4, has aninput connected to the output of the switch 706. The resistor R11 hasone terminal connected to the switch 706, and an opposing terminal ofthe resistor R11 is connected through the capacitor C4 to ground. Aneffect of the damping circuit represented by the resistor R11 andcapacitor C4 is that a slew rate of a signal provided on the output ofthe switch 706 is reduced. The switch 706 provides a square wave at itsoutput, and the damping circuit has an output that responds to thesquare wave in a non-square fashion. Specifically, the voltage on theoutput of the damping circuit increases more slowly than the voltageprovided to the input of the damping circuit.

The response voltage of the damping circuit is provided to an amplifierA5 with a gain of two, and then through a switch 708 to respectivesignal contacts 74S (see also reference numeral 74 in FIG. 4) of thedevices 300. Because the signal provided to the devices 300 is dampened,ringing can be reduced or be eliminated.

FIG. 31 illustrates a prior art solution, wherein a termination dampingcircuit is provided at a termination of one device. The terminationdamping circuit provides a dampening effect at the device that is beingtested. However, the functioning of the termination depends to a largeextent on the length of a line connected to the device that is beingtested. As illustrated in FIG. 30, the signal contacts 74S can be atdifferent distances from the damping circuit, as measured along a lengththat current flows in the circuit, and can be used without a terminationdamping circuit. Furthermore, the signal contacts 74S can be spaceddifferently from one application to another, for example, by 10 inchesin one application and 18 inches in another application, and the samedamping circuit will reduce ringing in each application.

While certain exemplary embodiments have been described and shown in theaccompanying drawings, it is to be understood that such embodiments aremerely illustrative and not restrictive of the current invention, andthat this invention is not restricted to the specific constructions andarrangements shown and described since modifications may occur to thoseordinarily skilled in the art.

1-104. (canceled)
 105. An apparatus for testing a device having anintegrated circuit, comprising: a frame including a base portion, andtest head and thermal system portions secured to the base portion; aholder secured to the base portion, the holder being capable of holdingthe device; a test head mounted to the test head portion in a positionsuch that electric signals can be sent through the test head to theintegrated circuit of the device; and a thermal system located in aposition to cool components of the test head, and being mounted throughthe thermal system portion to the base portion.
 106. The apparatus ofclaim 105, wherein the thermal system is mounted through the thermalsystem portion to the base portion without being mounted to the testhead portion.
 107. The apparatus of claim 105, wherein the test headincludes a test head support structure, a plurality of electriccomponents mounted to the test head support structure, and a panel thatforms a passage through which air can flow before flowing over theelectric components.
 108. The apparatus of claim 107, wherein theelectric components are boards, the test head support structure having aplurality of slots that hold the boards.
 109. The apparatus of claim107, wherein the thermal system includes a shell through which the aircan flow and at least one heat dissipation device in the shell, theshell forming an interface with the panel, with a gap being definedbetween the shell and the panel.
 110. The apparatus of claim 109,wherein the heat dissipation device includes a plurality of fins overwhich the air flows.
 111. The apparatus of claim 109, wherein thethermal system includes a fan that moves the air through the shell. 112.The apparatus of claim 111, wherein the thermal system includes avariable frequency drive to vary the speed of the fan.
 113. Theapparatus of claim 112, wherein the thermal system includes athermocouple in the test head portion, and wherein the variablefrequency drive varies the speed of the fan in accordance with ameasurement of the thermocouple.
 114. The apparatus of claim 105,wherein the thermal system portion and the test head portion are mountedfor pivotal movement relative to one another.
 115. The apparatus ofclaim 105, wherein the test head portion and thermal system portion aremounted on separate sets of arms.
 116. The apparatus of claim 105,wherein the test head portion and the thermal system portion aremechanically decoupled.
 117. An apparatus for testing a device having anintegrated circuit, comprising: a base portion; a holder for the devicemounted to the base portion; a test head portion and a thermal systemportion mounted to the base portion; a test head mounted to the testhead portion, the test head including a test head support structure, aplurality of electric components mounted to the test head supportstructure, and a panel that forms a passage through which air can flowbefore flowing over the electric components; and a thermal systemmounted through the thermal system frame to the base portion, thethermal system including a shell through which the air can flow and atleast one heat dissipation device in the shell, the shell forming aninterface with the panel, with a gap being defined between the shell andthe panel.
 118. The apparatus of claim 117, wherein the electriccomponents are boards, the test head support structure having aplurality of slots that hold the boards, and the thermal system includesa fan that moves the air through the shell.
 119. The apparatus of claim118, wherein the thermal system portion and the test head portion aremounted for pivotal movement relative to one another. 120.-230.(canceled)